I believed that people riding diesel locomotives (as opposed to steam or electric) were notorious for fighting with each other. I have no idea where this notion came from.
A childhood belief about trains

others believed things like this
- After seeing Thomas the Tank Engine, I believed that all the locomotives in the world had a face.— Joe
- My brother used to think "Kung-Fu Fighting" was actually "When It Comes To Fighting."— The Pacifist
- when i was little i believed that if you got three speeding tickets that you went to the electric chairAnon
- I used to believe that the "no outlet" sign on roads was a warning to people driving electric cars.— c
- I used to think that a conductor while conducting told the players what to play as opposed to their music.— Daryl
- When I was a child I used to believe that the steam rising from my food were ghosts. Anon