Have them drink a shot of the "Party Concoction" . That could be anything alcoholic, just put it in a huge pot and pour the drinks in front of everyone. We did that last year...it was fun because they didnt know what it was, they felt the pressure to do it, and the presentation builds the suspense. If you know how to use hot ice...even better.
You're going for "Try Not to be the Loser" incentives? Good idea...makes them participate. Have them act out a scene from a Horror movie, sing one of the kiddy songs like One Eyed One Horned Flying Purple People Eater. Or have them be the only person playing "Who Am I" (card pin/taped to their back with the name of character, famous person etc) and wear a dunce hat until they guess who the tag says they are.