What do you play?

This coming weekend, Decaffeinated and I will be trying our skills out at a Magic Pro Tour Qualifier event. Three weeks later, we’ll try again in a different form at the Regionals Magic event. For both events, card sleeves are required — these are plastic sleeves that go around the player cards and make sure that no wear or damage to any individual card makes it identifiable — basically, it keeps you from using marked cards (and marked sleeves can be swapped out easily enough).
Since I don’t own any sleeves, that meant a trip to the game store to pick some up. While I was paying, I chatted with the clerk, mentioned that I was going to go to Regionals for the first time, and he asked, “What do you play?”
I said I was still deciding, and he kind of laughed and said that he plays Izzetron.
I found that a singularly odd question. It’s as if I suggested going to get food somewhere, and a friend asked me, “What do you eat?” with the expectation that I’d answer, “Macaroni and cheese.” Given the huge pool of cards and all the interesting ways to play Magic, the concept of just having a specific deck that I always play feels as curious as having one specific food that I always eat.