Intolerant people. People who are pissed off if I am talking to a girl instead of lifting. (They wish they were talking to her instead.) People who rag on blacks, Mexicans, fat people, or beginner lifters.
On the other hand it does irritate me when people don't put their weights away. If you can lift the weight, you can rack it.
People with big egos thinking people of jealous of them.

Stereotypical individuals who make their culture look bad by emodying the worst characteristics.
Fat people doing ab work when they need to hit the treadmill for an hour.
Beginning lifters who think they know it all, use crappy form and ROM, and ask for a spot on a weight they can't handle.
But hey, dude you're so cool and jacked you should be able to clear up the weights for the abovementioned idiots you defend. You can even talk to the hot bitches while doing it. They'll think you're a real catch.
