Volleyball without hands

It's the classical volleyball, only you must not touch the ball with your hands. It's verry funny, and you can play in a pool, in a park or anywher.

Rules:

*You must not use your hands.

*You must throw the ball to the other side of the net.

*You must not touch the ball two or more times.

*You must score 21 times.

*You must not touch the net.

*Number of players: 5 to 20.