Watersnake is a game that needs two people or more within a larger group.
The rules are to insert a particularly unusual word or phrase into a conversation, like Watersnake for example and count who can say it most. The game ends if someone unaware of the game twigs on to the fact you keep saying the word.
"Mike and terry are coming, lets play watersnake."
When a male starts masturbating without an erection, much like playing with a watersnake. Upon arousal, he then uses a hammer to beat the erection back to a flaccid state. These steps are repeated until bleeding and ejaculation occur simultaneously.