I do think it's typical behavior.

Typical for guys in the locker room.

Typical for girls in the locker room, even.

And in those situations, typically done when kids are horsing around with friends. It crosses the line if someone of the same gender walks up and does it to a girl/boy they don't know very well, that they know will be embarrassed about it, or is someone that they are trying to make look foolish. It's one thing for a guy to depants his best friend in the locker room in front of their other teammates, good buddies all.

But NOT typical or acceptable, EVER, for one gender to do to another gender in the presence of people from both genders.

And sorry, call me old-fashioned, but I do think that makes a difference.