I'm really sick of these women who keep yakking, yakking, yakking during my workout classes. If you want to talk, do so after the class, not during a set.
(Yes, I said "women." I know this isn't politically correct, but for whatever reason, the men never do this sort of thing. It's always a group of women who can't shut up during the workout routine. Most of the women don't, but there's often a significant number whose mouths won't stop.)
A lot of people don't understand why this is a problem. "People need a time to socialize!" they say. Or worse, they say "If you find this distracting, that's your problem. Focus on what you're doing, not what others are doing." (Um, it's called "distracting" precisely because it does prevent others from focusing, morons.)