One of my biggest pet peeves is walking into a locker room and finding myself faced with a hefty helping of someone else's privates.
This may seem ridiculous - It's a locker room, after all; it's very function is for changing clothes, showering, aka nudity. But can we not have this nudity with some decorum? The thing that gets me peevish is the person who insists on sitting their every-such-thing rude and raw on the bench that I may later set my i-pod on (which touches my face) or my water bottle (which touches my mouth), or my hand (you get the idea). Or the person that is just lazing around in the full nude glancing over to catch a few minutes of Oprah while they lather on lotion in the jack knife position showing me things that probably only their doctor should see.
Taking this to the extreme is the person that actually makes themselves comfortable on the floor - yes, I have seen it. If that carpet could talk, well let me just tell you that it shouldn't be having that conversation with your reproductive organs.