I'll jump right to the idea.
It looks like the dodgeball we have now (red, round.)
A random person in the minigame starts with the ball.
When thrown and hits a block, it can get picked up again.
When thrown, the guy throwing loses the ball out of his inventory.
If the ball doesn't get thrown in about 5 seconds, the guy holding the ball gets killed, dropping the ball.
If the ball hits a player, the player instantly dies.
There could also be a ball wich could hit walls 2 times before being able to get picked up.
This would be useful for dodgeball TDM's/DM's where the host doesn't want a billion red balls flying everywhere all the time.