We brought out a spread of chocolates on a silver plate. It would also be effective to put them in an actual "assorted chocolates" box, but by this time the teens surely know you are up to something. I mean, they have already experienced frozen mayonnaise that was supposed to be ice cream, and they already fell once for the Twinkie eating contest, when they found out you had filled the Twinkies with mayonnaise...what's with the mayonnaise pranks?!!!
I didn't even try to fool them on this one. I just told them I would give them a prize if they finished one of the chocolates (no sneaking a little bite out of the corner like my family always does when we get a box of chocolates) and correctly guessed what was inside. Our prize is always "Atomic Money" which can be used to buy food and drinks from the concession bar.
The ingredients included: grapes, cherry tomatoes, chucks of cheese,...and several other items I can't remember (be creative!). It was worth the effort for a few laughs at the faces that were made. Most people who participated were able to guess properly, but there were a few we stumped.
Feel free to comment if you have any questions or suggestions to make regarding this activity. Hope it inspires a fun night with you and your group!