This wasn't annoying so much as bizarre ... I'd been working with this man (an African American man who aside from this incident was very intelligent) for weeks and one day he noticed my Delta keychain. He looks at me and asks me, in all seriousness: "Hey, you're black?"
The most annoying question I get asked a LOT is "Why didn't you join a white sorority?" I don't mind if Sorors ask me those sorts of questions; I expect that. But when someone (especially a member of an NPC group) asks me a question phrased like that, it really irks me - I wouldn't go up to them and ask them why they didn't choose my Sorority; it's rude. I also hate the insinuation that my decision must have somehow been a race thing. Like I joined Delta to insult white people everywhere or something.