A Simple Christmas Effect.

OK real simple using basic magic skills, write a prediction on the back of an ornament hang it on the tree. Force a card on someone, then magicians choice the ornament onto another spectator. It doesn't have be the whole tree, be all "Hmm what to do? Oh I know..." walk to the tree snatch off two ornaments and let some one else pick two more and then have another person eliminate ornaments until he has the prediction. Depending on your skills there are ways to ramp it up or down.