There's the one about a team that's just escaped from some bad guys by boat, their boat having sustained enough damage that it is taking on water, soon to sink. Their next choice? Everyone on the team decides it's a nice time to take a nap. Naturally, they all wake up floating as the boat sinks around them. Or maybe my favorite are the ones with the kill-crazy psychos. Wait, no, it was the one where someone thought it prudent to light off a flare in the middle of a natural gas pipeline.
You get the point. They were funny. And I'm wondering if you could re-create the funny intentionally.
Basically, gather people together for a normal game...obviously a throwaway, as you wouldn't want to waste a good solid campaign session on this idea. Everyone is told the premise of the game: One of you is a plant, meant to stir up as much ridiculous trouble as you can, in as subversive of a way as you can. By subversive, I mean that the plant shouldn't tip their hand until they get a good situation to blow to hell...like when the team stops for gas on the way to the run, and the plant decides that he absolutely must rob that gas station.
Yes, intentional anything doesn't breed humor, usually. But turning it into a game of 'react to the burning monkey' might be fun. Not as much fun as watching a truly stupid player self destruct, but fun none the less.