Here's some fun you can have with only your hand, and no, it's not called masturbation.
Chop Chop
Hand of pins
Between 2 fingers
The screwdriver game
Wearing bunch of rings on every fingers till the blood pressure kicks in, and your finger tips explode flying.
Hand is probably the part of our body that our eyes pay most attention to, and highly connected in a sensible level. So if something happens to it, we would feels the most. A genuine and instant response under the muscle of heart.
THANK YOU FOR DOING IT