What could possibly bring thousands of people from all over the world – including William Shatner – together for one week of good-natured mayhem? The humbly-titled Greatest International Scavenger Hunt the World Has Ever Seen (or, GISHWHES, for short), that's what.

GISHWHES is a week-long annual competition that involves multimedia submissions from teams of 15. And yes, Shatner recruited his own group to compete in this year's challenge – he seems pretty confident about winning the championship, according to his Twitter account header photo). The conceit is essentially this: teams need to artfully and imaginatively tick off the most items on a list of over 150 tasks.

Previous years' tasks have included edicts such as picturing Adam and Eve at a bus stop, throwing a puppet show at a children's hospital, creating a Sanitauras Rex, sharing an image of yoga skiing and snapping a shot of a Stormtrooper cleaning a pool next to a sunbather enjoying a cocktail.

This year's battle kicked off on August 2, and ends August 9, and the participants number in the thousands – it's sort of a no-brainer as to why: not only is the competition wacky fun, but the prize is pretty sweet. This year, the winning team will be flown to "King's Landing" in Croatia (yep, the infamous site where "Game of Thrones" scenes are filmed) where they'll board and set sail on a pirate ship and, "be treated to a survivor-style weekend adventure of revelry, mayhem and wondermentation." Whatever "wondermentation" means, we want to go there. Past winners have vacationed in Rome, British Columbia and even a haunted castle in Scotland.

Pretty amazing stuff, considering that the whole thing began in 2011 as a publicity stunt to help actor Misha Collins' show "Supernatural" win a People's Choice Award. It's now a five-time Guinness World Record-holding operation, and in the competition's fourth year Collins is looking to add three more world records to the GISHWHES trophy shelf.

Now that the game is under way, this year's task list is closed to non-participants, but you can follow the action at the GISHWHES Twitter (check the hashtag #GISHWHES) and Facebook accounts.

The best part about the GISHWHES program – aside from the fact that it encourages teamwork, International good will and crazy fun – is that the proceeds from entry fees are donated to Collin's charity Random Acts, a non-profit dedicated to promoting random acts of kindness.