I used to work as a parking lot attendent in a downtown on weekend in the city where I was doing my masters in USA ..
parking lot was close to night clubs and bars. Two girls came to me and ask me to permit them to sit between parked cars (to hide themselves) and pee .. off course as a gentleman. I permited them to do so :D
so its not that girls dont do that when they can
man do u have stories to tell dont u