No one said it?
Tie piano wire around your neck, and connect the other end to the top of a bridge. You then superglue your hands to your head, and wait for them to dry. Then, jump.
The piano wire should rip your head off your body, but your glued hands will stay connected and holding your head.
The first person to see the corpse will be like "Dude! That fucker just ripped his head off!" because your body will be laying there with your head between your hands.