Check out these nine gym sins on Newsweek when you get a chance. As in right effin' now. Seriously, what else are you doing? You're reading my crap, right? Might as well read something from a reputable source.
Now that you've read it (you have, right? If not, go back right now! Jill!), I guess it's a good time to ask if it's common practice, when asked to spot someone on a bench press, to tea bag him. Common courtesy, right?