Make your own tinfoil portraits/sculptures. You could buy face masks and give students tinfoil. I think this would work. Would probably look even better on a black canvas or cheaper option, black card.
Jello Worms - Tie a bunch of straws together. pur gelatin into straws. let it sit over night in the fridge. take the straws and let gelatin slide out AND THERE YOU GO! You have jello worms! How to Eat Fried Worms. (Maybe jello shot worms.