Well, if you were a geek, and you looked like a geek, chances are you were bullied in school because of it, and probably by someone who looked like you, op. Not specifically black, of course, but someone who doesn't look like a geek, probably someone fairly athletic. People constantly criticise the tendency to judge a ton of people by a minority, but it's kinda natural. If we touch a cactus, it hurts, and we become afraid to touch something that looks realistically like a cactus, even if we downright know it isn't. Hell, I was bullied by a group of people who were in a band in school, and I became nervous around people who I knew were in bands.
Basically, we geeks are antelope, and you're the antelope that put on a lion costume.
At least, that's my theory. Personally, I'm always a little cautious around someone who could, if they wanted to, kick my ass, but these days I know better than to instantly assume that because someone has the ability to hurt me, they'll do it.
) and from our perspective, you seem like you're not really enjoying the stuff we love and whatnot and that feels both dismissive and kinda pretentious. I'm not trying to attack you here or anything lol, just trying to explain how they might have felt about you. They'd probably take your lack of over-the-top enthusiasm at the whatever activity took place as a personal insult and treated you based on that. 
