Benidorm or Bust Challenge. The group is one of 199 other teams taking part in the challenge. They're making the run for charity. Interesting point(?) they're going to be in character, wearing Scooby Doo outfits throughout the trip.
"You know what makes me really sick to my stomach? It's watching you stuff your face with those hotdogs! Nobody - I mean nobody puts ketchup on a hot dog!" Clint Eastwood, Sudden Impact