Grilled Cheese Prank
Make your victim think you just made him a delicious grilled cheese sandwich, but in reality its actually a sweet dessert. For the bread just use pound cake bread and for the cheese, use white frosting that you color yellow with food coloring.

Butter Experiment
What you do is this " say I did an experiment and look if you put salt on butter the butter heats up, here put your hand over it. Then when the person puts their hand close enough, push their hand in the butter!"