Just because you think your little darling is not old enough to go in the men's locker by himself, doesn't mean he's young enough to be in the women's locker room. If he's old enough to leer, he's out.
Excellent rule! I was drying after my shower one time and looked down to see a little male child watching me from under the stall, he was around six or so. I tore his mother a new one.