Celebrities are like speed cameras; they can pop up anywhere and anytime.
But if you're really serious about getting your picture taken in the company of one - a celebrity that is - you can improve your chances by heading to certain locations. Think airports, luxury hotels, upmarket nightclubs, shopping precincts or pretty much anywhere in Los Angeles and New York.
To help celebrity spotters improve their chances of spotting a big-name, Flight Centre asked its people who they had bumped into during their global travels and where.
The Ski Slopes
Like everyone, celebrities sometimes need a break. And there's "snow" better place to unwind in winter than Canada's world famous ski fields.
While working at Whistler's famous Rendezvous Lodge, Flight Centre Australia general manager Tom Walley cooked up a barbecue that was almost fit for a king.
"I was working there as a cashier in the late 1990s and we would often have barbecues outside when the weather was fine," Tom said.
"On this particular day, Prince Charles and the two young princes were skiing at Whistler.
"We'd been given the rundown as to the protocol. For example, only speak to them if they speak to you.
"We were cooking outside and he (Prince Charles) walked past, so I introduced myself.
"We talked for five minutes or so about Australia and he came back past to say goodbye as he left."
While Tom rubbed shoulders with the Prince of Wales, Flight Centre e-commerce leader Sean Sutherland caught a close-up view of unofficial Hollywood royalty - Brad Pitt and Angelina Jolie - during a visit to Los Angeles.
"I was staying at the Hollywood Roosevelt Hotel, opposite the Chinese Theater where the Oliver Stone film Alexander was opening," Sean said.
"Two work colleagues and I snuck into the after party, which was being held at The Roosevelt, via a service elevator that staff members were using.
"I was eventually discovered and kicked out, but I managed to get back in and later made it to another party in Oliver Stone's penthouse.
"We initially told people we worked in special effects, but that was prompting too many questions so we ended up saying we were lawyers.
"We stood fairly close to Angelina Jolie, who was in the movie, and Brad Pitt, plus Colin Farrell and Val Kilmer."
At 30,000 Feet
Not every celebrity has the luxury of a private jet, so keep your eyes peeled in the sky.
Sam Cook (firstname.lastname@example.org), from Flight Centre Business Travel at 360 Queen Street in Brisbane, shared air space and a quick conversation with Angelina on a Qantas flight from Sydney to Los Angeles.
"She boarded the plane with her children and I asked if she wanted a hand with her bags and if she was having a nice day," Sam said. "She responded saying it was all good and she thanked me for the offer and also asked if I was having a nice day."
Airports also proved a prime celebrity spotting location for Tanya Ilkin (email@example.com), the team leader at Flight Centre Kirribilli.
Tanya caught up with a Kardashian at Miami Airport and tennis ace Andre Agassi in Las Vegas.
"I'm a reality show junkie and as soon as someone said 'there's Khloe Kardashian' I walked over to her and asked if she'd pose in a photo with me," Tanya said.
"She was very friendly. We had a little laugh and then I left her alone.
"When I saw Andre, my two gorgeous Ukrainian girlfriends and I were travelling from Vegas to Toronto and he was sitting on the floor near the gate in the airport, just like any normal passenger.
"I really wanted to walk over to him and ask for a photo then but thought 'calm down Tanya, when you land girl'.
"We upgraded our tickets to first class at the airport and ended up sitting next to him.
"He was looking at photos of his wife, Steffi (Graf) and watching videos of his kids on his laptop.
"I saw my opportunity to talk to him when we landed and were walking to the baggage claim.
"Andre had been the guest speaker at a Flight Centre conference I attended in Vegas in 2010 so I thought that was a great intro.
"I congratulated him on his speech and then my lovely girlfriends and I posed for a photo with him. Such a nice celeb."
Nicholas Pearson (firstname.lastname@example.org), from Flight Centre Capital in the ACT, caught up with Kylie Minogue on a Qantas international flight, while Flight Centre chief financial officer Andrew Flannery saw musician Alicia Keys on a flight from London to New York.
Nicholas Lalak (email@example.com), from Flight Centre Strathfield, queued with English actor Simon Pegg at Los Angeles International Airport (LAX).
"He was going through immigration just before me at LAX," Nicholas said.
" I asked him for a photo and he was very friendly to oblige.
"We weren't allowed to take the photo in the area where we were queuing, so he went ahead to a spot where it was allowed and he waited until I was finished. Incredibly nice man."
Chloe Elliott (firstname.lastname@example.org), from Flight Centre Concord in NSW, caught Robert De Niro's eye at Melbourne Airport.
"I walked out of the airport waiting for my ride to pick me up and all of a sudden paparazzi were running out near the car park," Chloe said.
" I was looking around to see what the go was, then Robert Di Niro came out looking scraggly with a beard.
"I had just returned from Bali and was in short shorts and a singlet in the freezing winter of Melbourne and he came up to me and said: 'bit cold are we?' and walked off.
"Bloody hilarious and embarrassing at the same time."
Flight Centre Travel Group global corporate leader Rob Flint says Heathrow airport's lounges are another good place to spot big-names.
"A couple of years ago, I was in a lounge in Heathrow Terminal 5 and was sitting near Eric Clapton," he said.
"He was talking to another musician and was drinking from his own collection of wine. They kept it there for him at the lounge.
"On a separate visit, I saw actor Robert Pattinson with a minder in the same lounge.
"I was also on a flight from Los Angeles to Brisbane with Orlando Bloom and his baby."
More consultant tales: Making Dreams Come True At Disney World
Movie-inspired travel: Silver Screen Inspiration: On-Location Holidays
On The Movie Set
Of course, you're virtually assured of seeing a famous face on a movie set.
She didn't know it at the time, but Melanie Schinkel (email@example.com), from Flight Centre Macarthur Central in Brisbane, met Andy Garcia on the set of the movie Let's Be Cops on the Sunset Strip.
"During my stay in LA, I thought it would be cool to work on a real movie set," Melanie said.
"I found an ad on Craigslist for extras that were needed for a music video, so I applied and was offered the gig.
"When I arrived, it wasn't a music video at all. I was to be an extra playing a goth girl in the major comedy motion picture.
"I was rushed off to the make-up department and afterwards, while filling out my paperwork, got talking to one of my fellow extras, or so I thought, after asking to borrow a pen.
"The guy was in his mid 40s and for some reason looked really familiar. He said his name was Andrew and I proceeded to chat to him for about two hours while waiting for my scene.
"Andrew was really friendly, interested about Australia, and I asked him a lot of questions about how much acting work he gets, who is his acting mentor et cetera.
"We chatted, shot our scenes and then said our goodbyes.
"I didn't realise until the next morning, when my husband looked up Let's Be Cops, that I had actually been chatting to Andy Garcia.
"I was so embarrassed about the questions I had asked him, but he didn't let on that he was famous at all.
"From then on, every time I walked past Andy's star on the Hollywood Walk of Fame it just made me laugh. Do you get much acting work? Geez, I wonder!"
Shane Pinder, from Flight Centre Erina B at Erina Fair Shopping Centre, was equally surprised to learn that he spoke to Vince Vaughn during a break from filming scenes at a youth hostel in Boston.
"After a long day of travelling from Maine down to Boston and dealing with a hangover from the previous night, I was less than ecstatic to arrive at my hostel and to be told I had to wait 10 minutes before I could enter because a film was being shot inside," Shane said.
"Assuming that it was a budget film, it didn't really interest me. All I wanted was a shower.
"When I eventually made it into the hostel, the line for the reception was as epic as the set work surrounding the adjacent social area.
"After another 15 minutes of waiting in line, I made it to the counter in time for the director to call silence within the room, even though we were behind a black curtain. I basically had to check-in using sign language.
"After my shower, I wandered downstairs, exited the lift and bumped into a familiar face. Without realizing who it was, I blurted out: 'Hey man, how have you been?'.
"He replied casually and, without thinking, I walked outside. I got about half way down the street when it kicked in - it was Vince Vaughn.
"The Movie was called Unfinished Business. I haven't had the chance to see it yet but there were some pretty cool action scenes filmed inside the HI Hostel in Boston."
Bronwyn Wareham (firstname.lastname@example.org), from Flight Centre Kingston in the ACT, saw former basketball star and actor Dennis Rodman filming scenes on a court at Venice Beach, while Michael Donaghy (email@example.com), from Flight Centre Picton in New South Wales, saw Alex O'Loughlin in Hawaii.
"I was walking down the old international market place in Honolulu and they were filming an episode of the new version of Hawaii Five-0 and I met him while they were in between scenes," Michael said. "I met some of the other members of the cast as well, Grace Park and Daniel Dae Kim."
If you can score an invite to G'day USA in Los Angeles, you're also certain to see a celebrity or three.
Vanessa Franich (firstname.lastname@example.org), from Flight Centre Galleria in WA, met The Mentalist, Simon Baker, at the 2012 event, while Tracey Heazlett (email@example.com), from Flight Centre Tamworth, said g'day to Grease star and Qantas global ambassador John Travlota.
"There were lots of celebs around and, after a bit of a walk around and a few photos with Miranda Kerr and the like, we came across a table that was surrounded by security," Tracey said.
"Sitting at the table were Jon Voight, Kelly Preston, Tim Allen and John Travolta. Security was not letting anyone even close.
"The gods were on my side as, just as Tim Allen hopped up for a moment, all the security guards looked away and I was in.
"I sat down next to him and said 'excuse me Mr Travolta, can I have a photo please?' He was a little shocked but said 'sure'.
"He was really nice about it especially since I was not supposed to be there."
New York's Streets And Restaurants
The Big Apple is a big drawcard for celebrities.
Flight Centre Travel Group's managing director in Australia, Melanie Waters-Ryan, dined at a table next to Liza Minnelli at Dovetail restaurant on Manhattan's Upper West Side.
She also narrowly avoided a sidewalk collision with former US president Bill Clinton and daughter Chelsea outside The Modern, a popular restaurant on West 53rd Street.
Rachael Deede, an Aussie who lived on the Upper West Side while working for Flight Centre in the USA, says she frequently sees Manhattan-based celebrities in their local neighbourhoods.
"The thing about celebs who live in NYC is that they don't tend to hang out in the swanky places so much," Rachael said.
"You will often see them in their local neighbourhoods, where they are not bothered by the paparazzi.
"Brooklyn and Williamsburg are great places to look. Try cafes like Cafe Mogidor - cool French Moroccan - where you may see hip young actors like Benjamin McKenzie (Gotham and the OC), who live nearby. Michelle Williams is another local.
"The Keith McNally restaurants - Balthazar and his newest Cherche Midi on Bowery - are always good for people watching.
"The West Village has many haunts where you might see the likes of SJP (Sarah Jessica Parker) on the streets, as I did a couple of months ago."
Belinda Ayubi (firstname.lastname@example.org), from Flight Centre Dee Why, hit the celebrity spotting jackpot in Las Vegas.
"My boyfriend and I got into The Venetian lift to head up to our room, when two guys and a girl walked into the lift with us," Belinda said.
" I kept looking over to the girl - she had sunglasses on - trying to work out where I knew her from.
"During this time, my boyfriend kept nudging me trying to get my attention. When I looked at the guy who was with her, my mouth dropped open as I realized it was Justin Timberlake with Jessica Biel.
"He gave me a smile and a quick hello before they had reached their level and got out."
Anthony Michael (email@example.com), from Flight Centre Bateau Bay, saw Mike Tyson as he was leaving a signing at a sports store on Vegas's Miracle Mile.
"I bumped into him outside the sports store I always go to when I am there," Anthony said. "I had met him before and he actually remembered me so I got him to sign a few things and got a photograph back in the sports store so he didn't get harassed."
Flight Centre Bateau Bay's Gillian Crawford (firstname.lastname@example.org), and Flight Centre Wodonga's Sabrina Crowe (email@example.com) had close encounters of the shopping kind in London.
"I was in the street outside Harrods and Colin Farrell walked out of the store's rear exit," Gillian said.
"He stood next to me and lit a cigarette.
"I smiled at him and nearly fainted. He smiled back, then walked off.
"I think I stood there for about 15 minutes with a stupid look on my face before I could actually move."
Gillian also spent time behind the counter at London's most famous department store and saw a string of big-name shoppers.
"I was on a working holiday and at Harrods for a year, so I served many celebrities in that time including Michael Caine, Gwen Stefani, Ronnie Corbett, Delta Goodrem, Anthony Stuart Head and Ronan Keating, who was a regular."
Sabrina was in Topshop (Oxford Circus) when one of music's biggest names dropped in.
"The staff seemed really excited and were looking around. There also seemed to be more security than usual around," Sabrina said.
"It turned out that Rihanna was getting shown through to the private fitting rooms. I saw her pass through, surrounded by a crowd of security and personal assistants."
Theme Parks And Tourist Attractions
Just because you're at a popular tourist attraction with thousands of other people, don't think you won't stumble upon a celebrity.
Bec Ellison (firstname.lastname@example.org), from Flight Centre at 545 Queen Street Brisbane, chatted to Whoopi Goldberg at Disneyworld in Orlando.
"I was working in the candy shop at Disneyworld in 2012 and Whoopi was in a line waiting for some food," Bec said.
"She noticed my name badge which said 'Becky from Brisbane Australia', told me how much she loved Australia and asked how I was enjoying America.
"I was very star-struck, went red in the face and giggled a lot."
Matthew Welsby (email@example.com), from Flight Centre Oxley in Brisbane, saw both Christopher Meloni (Law and Order SVU) and Dean Norris (Under the Dome, Breaking Bad) at Universal Studios and Aussie actor Nathin Butler (Winners and Losers) at the Griffith Observatory.
"We were at Universal Studios and he (Christopher Meloni) was promoting a new movie that was coming out," Matthew said. "I am a massive SVU fan so I thought it would be awesome to get a photo."
Nightclubs And Pubs
Stacey Martin (firstname.lastname@example.org), from Flight Centre Mackay in Caneland Central, rubbed shoulders with the likes of Flo Rida and Ke$ha, while she worked in an open air nightclub in Beirut called Pier 7.
"We had heaps of celebrities visit, perform and party at our nightclub," Stacey said.
" I was the manager of the private suites and all performers were allocated one suite for their entourage to party after their show.
"Flo Rida was the highlight and the biggest party animal with his entourage staying till sunrise and drinking copious amounts of Dom Perignon Rose .. ."
Robert Samway (email@example.com), from Flight Centre Potts Point, spotted David Spade at Rock and Reilly's Irish Pub on Sunset Boulevard in West Hollywood.
"He was having a drink with a guy who I was later told was Chris Farley's brother," Robert said.
Playgrounds Of The Rich & Famous
Of course, there are also locations throughout the world that have magnetic appeal for celebrities. Examples in Australia include Noosa, Sydney and Byron Bay.
Overseas, head for a luxury island resort or perhaps the French Riviera, which was where Jason Norris (firstname.lastname@example.org), from Flight Centre Ulladulla, dined alongside Tommy Hilfiger.
"I was at a restaurant in St Tropez having lunch at the beach and on the table to the left of me was Tommy Hilfiger," Jason said.
"I realized then and there that I was officially in the playground of the rich and famous and dining with a guy who makes really awesome clothes."
Bali is another popular haunt for holidaying celebrities and sports stars.
Allisa O'Connell, the head of Flight Centre's Infinity Holidays' wholesale business, shared a fence with former rugby league player Braith Anasta and his actress wife, Jodi Gordon, following their wedding in Bali in 2012.
"We were staying in the Sentosa Villas in Seminyak and they were in the neighbouring villa," Allisa said. 'Quite a few rugby league players were also there for the wedding."