Intentional, pride-filled ignorance. See Chris Rock's discussion on the phrase "keepin' it real".
Atonality. Whether it's Philip Glass or modern electronica/techno, I prefer my music, well...more musical. Atonal music makes my ears bleed.
People who use their personal tastes to make value judgments about others. I'd rather not be stereotyped as a mouth-breathing Neanderthal because I actually LIKE Madden, thanks, and i'll try not to call you names if you like anime and JRPGs, OK?
There are more---I'm not the most tolerant sort, but it's Friday and that means games!