Could always try a 'prisoner's dilemma' type question. You and your party have been arrested for stealing an artifact. You are guilty.

Oh gosh, I remember the 'push the button and your friend gets killed' variant of that. Unfortunately, this now means I want to quote completely irrelevant Baldur's Gate II lines. "BUTTONS ARE NOT HOW ONE ESCAPES CAGES!"

But I'm slightly against prisoner's dilemma because it involves ratting on your team mates and, you know, team game. Probably isn't going to help team cohesion, even though it's all in fun. XD