Due to some of the major trauma's that I have experienced as a small child I cannot go into a restroom without a transitional object. When I was younger I could not use the house restroom (or shower/bath tub) without taking one of my birds in with me. Now, since I moved in with my boyfriend, I cannot take a shower or use the "bowl" without my cat Algiz.
As for public restrooms, elementary school ones are out of the question! Other restrooms I use, but my cat Algiz still comes in with me because he is my service animal. I also keep a Raven finger puppet in my bag (that I named Beetlejuice) and situate him either on the septic tank, my bag, or on the toilet paper rolls (which ever one is clean).
The reason why is due to part of a trauma I experienced in elementary school. The girls would try to beat me in the stall, or they would gang up and slam the sides of the stall I'd be using. I was also sexually abused in the same bathroom when I was in the first grade.
I use my cat or Beetlejuice to distract me from flash backs, and to make me feel safe and less venerable.