Author J. K. Rowling claims to have invented the game in a small Manchester hotel after a fight with her boyfriend. Makes sense.
Believe it or not, quidditch is also played in the real world. There is even an International Quidditch Association, complete with its own set of official rules. The IQA is a registered 501(c)3 nonprofit organization, and its "mission is to promote, develop, and govern the sport of quidditch and inspire young people to lead physically active and socially engaged lives."
In case you're wondering what a game of quidditch played by a bunch of muggles might be like, take a look at this match between UCLA and Emerson:
OK, so it's much more exciting in the world of fiction. But then again, what isn't?