Find a Rubber band. - Joke

Find a Rubber band (not a really thin one or a fat one) twist up the rubber band (more the merrier) twist until it is a tight coil when you pull the 2 sides, and then find a victim with long hair (shaggy is good). Pull the rubber band apart while still being coiled and then release it in their hair, this will make their hair scrunch up and hurt a lot in the process of trying to pull the rubber band out.