I used to think that the theme song for the Brady Bunch said "They were born and living all together" instead of "they were four men living all together." I could never understand why the lyrics made so little sense!
A childhood belief about misheard lyrics

others believed things like this
- I used to think that the actors on tv shows sang the show's theme song.Anon
- Until I was about 15, I beleived my Father was the person who sang the "Cheers" TV Show Theme Song.— Dustin
- That there was a zombie living behind the bathtub in the upstairs bathroom.Anon
- I used to believe the living room furniture would party after we all went to sleep.— Ellen
- When I was a child I used to believe that there were dinosaurs living in the mountains near where I live.— Teacher LM
- When I was younger I used to believe that when I hit an object they would feel pain like they were living.— Alice