On a recent visit to the University of Colorado, Boulder, I saw some students playing a sport I've never seen before. I'll do my best to describe it.
On a grass field, a rectangle is marked out with string, about 5m by 10m. Inside the rectangle are six balls, about 20 cm in diameter, three red and three blue, placed at specific locations. There are four players, who start out standing outside the rectangle: three at one of the short edges (marked X below) and one at a long edge (marked O). Here is a very crude drawing.
In addition to the four players, there is a fifth person who seems to be a judge.
The play of the game appears to go as follows. The judge calls "Go", and the X players try to run into the rectangle, pick up a ball, and return to their original position. When one of them picks up a ball, the O player runs into the rectangle and tries to tag him.
There seems to be some rules or strategy governing how they do this. The X players can wait...