There is, in fact, an ACTUAL National Quidditch League and an International Quidditch Association. They even have a World Cup (like in Harry Potter and the Goblet of Fire). The International Rules are based on a game devised at Middlebury College in 2005, and it's now the basic model used throughout the United Kingdom, the United States and much of the rest of the world. Obviously, no magical Golden Snitches (which are supposed to be quasi-sentient, flying balls) are available, so instead individual players take on the role. Everyone is still required to run around on brooms, however.
Yes, that's right. People are running around on brooms in this sport, kind of like our grandparents used to do with those toy horses that freakishly were just a creepy-looking, lifeless, severed horse head at the end of a broom handle.
Read about the other things from Harry Potter that have become a part of the real world at Ranker. Link -Thanks, Brian!