Parachute, plastic bouncing balls
You need a parachute – no strings – with a hole in the middle, and 20 or more bouncing balls (the plastic kind in Toys-R-US)- one for each player.
Number the balls and assign one to each player. Every player places his/her ball on the parachute and everyone grabs and lifts the parachute with two hands. Then everyone starts (usually after the gym teacher says “GO!”) pumping the chute up and down to remove the balls.
The player with their ball on the chute last, wins.