The old Incredible Hulk show was a big favorite in my grade school. Enough so that I sincerely believed that the Hulk himself lived in the girl's bathroom, and that was why you couldn't go in there.
My teachers were pretty obvious playing favorites, so it made perfect sense that the girls would get to know about the Hulk, and we wouldn't.
I think I stopped believing in this one, embarassingly enough, because everyone started being 'way into The Dukes of Hazzard instead.
A childhood belief about classes

others believed things like this
- I always thought that the Hulk was based of Hulk Hogan. — Vijay
- I used to believe that God was the Incredible Hulk - he was green and muscly and had purple trousers.— Emma
- I used to think "Hulk Hogan" was really "Haul Kogan" before I knew his name!— Christy
- my friend thought that the film 'the hulk' was about the jolly green giant from the sweetcorn adverts.— patticus
- I thought that when you pressed the hazzard button in the car, the dukes of hazzard would come and save you.— smfd26
- I believed that our teachers lived at school. They were teachers--they had no reason to leave :)(Anon