Right up there with being woken up in the middle of the night by someone jacking off, rather vigorously, in the youth hostel. Kind of takes the cachet off of 'meeting interesting people from foreign countries'....
To continue the gym thread: "Hey, dumbass. If you can lift all that weight you can certainly rack it when you're done. Or do you let your momma pick up after you?"
And finally: "No, I really don't need for you to describe the wonders of your penis pump, which you are holding in your hand, while you're standing naked in the locker room, you old perv."