Privacy
Those of us who live with kids know that being alone in the bathroom is a infrequent luxury. Frankly, it really only happens when you're the only one at home and if you own cats, you can forget about it then too. It's useless to lock the door because then your child will stand outside the door knocking, calling to you, asking how long you're going to be or if you know where xxx is. So you will appreciate how hard it was not to laugh the other morning when I walked into the bathroom when C was taking his morning pee and was greeted with "Can't a man get a little privacy around here?"