In our locker room, we frequently stripped down completely and changed underwear. In fact, girls that didn't change their panties after gym were made fun of (so silly.. ugh!). Not sure if the boys stripped down completely or not, but MANY of them did shower, so..
That said, I spoke with DH about this years ago. He said what Jessica said above.. he said that if a guy were to notice another guys penis, that the first guy who noticed
would be made fun of. He said he never looked at other guys, as he just wasn't interested and he was too busy changing his own clothes and making it to his next class.
I don't know. Even if my boys were going to be made fun of in the locker room, I'd still prefer not to circ them. I don't want them made fun of, but I'd rather they keep their penis' intact. As I genuinely feel that later on, even if they never say it to myself or DH, they'll be thankful we didn't cut anything off. I know now that DH has researched this (well, five years ago when we found out we were having twin boys) - he wishes his Mom hadn't circ'd him in the first place.
At least if my boys want to be circ'd later on for whatever reason, they can have it done. But getting their skin back, while restoration is possible, it's easier to just not be circ'd to begin with, kwim? And of course, the main MDC line about circ'ing, which I agree with - it's not my penis to do with as I please. So why should I, even as their Mother, get to choose if such a drastic thing is done? It should be up to them when they are old enough to make such a decision.
And now that I've rambled....