On vacation we went to a brew pup and the bathrooms were labeled "hops" and "barley". Luckily we were sitting close enough to them that I could wait and see where people went before I had to go.
Oh, and there are the restuarants like Texas Roadhouse or Logans Roadhouse that on the back of the door it has the opposite sex so as you are leaving the restroom it looks like you came into the wrong one.

I have a friend that did that at a Carls Jr when we were in high school. She was SOOO embarrassed.