I told my little sister, when she was 6 (she's 11 now) that I went to Hogwarts School of Witchcraft and Wizardry and for aaaaaages she believed me. I had a Harry Potter bag with the Hogwarts Crest on it and she said to me "woow Dumbledore must be really happy that you have a bag with the Hogwarts Crest on" I agreed with her and showed her the wand I bought from Diagon Alley, which was actually a stick I found in my garden! She still denies she ever believed me!
A childhood belief about classes

others believed things like this
- I used to believe that I would go to Hogwarts. Anon
- i used to believe i would get my letter to hogwarts when i turned 11— katie Phillips
- I waited for the mail to come on my 11th birthday so that I could get my letter to Hogwarts... It never came.— Charlie
- the summer that I turned 11 I waited out side on the step all summer for my hogwarts letter... ;D — Ginny weasley... not really
- i used to believe Harry Potter was real— charlotte
- i believed that thunder and lightning came out of the alley across the street from my house.Anon