So, unless the guy was wearing skin-colored tight suit or something, then yes. I do believe he was naked. Also, he was taking a shower... Pretty sure most people are naked when they take showers to clean themselves.
Hmm, dunno. But it'd be a shame not to watch it. Yes, it's an immature adult joke but he's full-on naked. The screen usually cuts of where his torso connects the waist, so I really don't see a problem with it.