A sexual act in which two consenting males (of legal or illegal age) sit on their hands until they become numb. When both achieve sufficient stiffness of their penis they simultaneously jerk each other off until the point of ejaculation. At this point both loads of cum are then blasted into each others faces.
This game can be played by oneself, but is usually referred to as the strange in such cases.
My little brother woke up and said his hand was asleep so I sat on my hand for a while and put our sleeping hands to use and played numby dicks all morning.
I would die to have played numby dicks with Simon Birch.