I was maybe 8 years old when I saw my first (and only)nasty bathroom experience, this was probably also my first experience in an American store too.
I was at a Target or Walmart and I went into the bathroom. As you go through the door there is a stall wall that blocks your view from the rest of the bathroom. I remember when I walked in that it smelled horrible, and I said out loud " it stinks!", and said it really loudly. Then I turned the corner and witnessed one of the most crazy things ever in my life to this point of my life. Shit was spread out all over the bathroom. Little chunks about two inches in diameter on the the floor, streaks were streaming over the walls and mirrors. I stood there for like 10 seconds looking in awe before I noticed a rather large woman burning a hole through my soul as she looked at me. I locked up, and I couldn't move. She said to me "You need to leave." And she then returned cleaning the mess.. with toilet paper. After that I can't remember anything that occurred, I don't know if I used the urinal or anything.
A more humorous story, or at least it is funny to me. When I was in high school, I was in the bathroom and the janitor was in there doing regular cleaning stuff, I guess. He going through the bathroom and I guess he decided that he needed to take a shit. So he went into a stall, and right away I hear "What is this?!" I'm looking in the mirror to look back at his stall, and he comes out and makes eye contact with me and says "Acting like someone wants to see they shit" He was pissed off, and I'm pretty sure he thought for whatever reason that I was the perpetrator.
Those are my lame stories.