College students playing real-life quidditch (minus the flying):

The Amherst College Acromantulas played host to the Middlebury College Mollywobbles on Friday. This was the Acromantulas's first match as part of the Intercollegiate Quidditch Association.

This USA Today story explains how the rules are adapted to the non-magical world:

So, here's how Quidditch is played according to earthbound rules:

Brooms are required, leaving only one hand available, making the game harder as you chase the game ball, a slightly deflated volleyball.

Each team has seven players.

Three chasers throw the ball among them as they work down the field. If they get it through one of three circular goals (think hula hoops on poles), the team scores 10 points.

At the same time, two other team members fling around dark balls called bludgers in an attempt to distract and knock over opposing players. When a player is hit with a bludger, he must drop any ball he is holding and run back to his goal zone before he can make any more plays.

Seekers try to catch the most elusive ball, the Golden Snitch. In the Rowling books, the Snitch flies about independently. In real life, it hangs in a sock from the shorts of a player selected for fleetness of foot. The Snitch disappears for periods of time, reappearing on the field to shrieks of the crowd. The Snitch player has a much larger boundary than the others, often covering a large part of campus. Seekers can follow him. Catching the Snitch is worth 50 points, and once the Snitch is caught, the game ends.