Have some leaders ready to act as referees to help settle disputes in case students argue over whatever chaotic course of events may unfold.
Start each student off on the the far end of the room against the wall.
Give each student a sweet potato and a plastic spoon. Their job is to roll the sweet potato along the ground using the spoon in their mouth.
The first person to cross the finish line (you can put a piece of painters tape down towards the other end of the room) wins.
Enjoy the traffic jams that ensure as wobbly yams go in inconvenient directions and students get in the way of one another.
Have students push with their nose instead of with spoons in their mouths.
Instead of a finish line consider setting up three goals on the other side of the room. The first person to get their potato in a goal wins. Each goal can have one winner only. This way there will be three winners and students will have to strategically decide which goal to go after.