What's in my shower???

I have this thing where if I'm in a bathroom with a closed shower curtain, I have to look behind it just to be sure my life isn't in danger. Which begs the question, what are the scariest things that could be lurking back there?
  1. Various monsters from film and tv
  2. Ghosts
  3. Squatters
  4. A crowded room of people I don't know
    Actual worst fear
  5. The mean kids I went to middle school with
  6. A jar of mayonnaise
    It's a texture thing...
  7. The Divergent series on an endless loop
    I'd rather take the mayonnaise
  8. Dude Bros
  9. The Giant Lumberjack on the Side of the Highway
  10. The Mona Lisa
    Her eyes won't stop following me!
  11. 90s Internet