I did it at our YMCA, when the women's locker room was closed for a short time and we were to use the rest rooms down the hall. There was even a male lifeguard standing outside talking to someone and I just barreled on it!!
Another restroom story - if you to Chimney Rock State Park in I think (South? North?) Carolina, and you go all the way to the top to see the views from the top of the Rock, check out the restrooms in the gift shop up there. It was beautifully painted in a scene of a forest, mountains, with animals, creeks, - very pretty. I washed my hands and turned around to where I thought exit door was. it was all painted, too. By looking for door closing mechanism at the top of the door, I found it and made my way out. I was told the men's room was painted the same way.