Hold a Wet Sponge Toss
Remember that great scene at the end of "Grease" (the first one) in which Coach Calhoun (Sid Caesar) got a pie in the face? In the film, the pie booth was raising money for the teacher's fund. It's a classic idea: Embarrass or otherwise tease a teacher, community leader or boss for a great cause. The pie throwing idea can get really messy, though, so lose the gooey filling in favor of a wet sponge. The reverberating smack when it hits will do the trick, and cleanup will be a breeze.