In England it's common for football (soccer) fans to declare their team allegiance by saying "I'm X" rather than "I'm an X supporter". For example today I overheard this snippet of conversation: Football supporter 1: "Are you Liverpool?" Football supporter 2: "No, I'm Arsenal." It's as if the team defines an entire person. Where and how did this turn of phrase evolve, and is it common with any other sports in other places?
What is the origin of the phrase "It's on like Donkey Kong"? [more inside]