Something you could do in a trampoline to hurt a guy?
Whack him in the balls while you're jumping around ! Be careful !
Why do you want to hurt someone?
Dangerous... don't even think about it. You can break bones fooling around with a trampoline.
Don't hurt people... That's not nice :|
1. Knee him in the groin.2. Bite him on the arm.3. Pull the trampoline out from under him when he's in midair.4. Shank him.5. Tell him you've been having a torrid affair with his wife and his kids aren't really his.