When I was little i used to the song Achey Breaky Heart would go "My achey breaky heart makes me wanna fart."
I later found out I was wrong when i said it in kindergarten.
A childhood belief about misheard lyrics

others believed things like this
- The song called heart of glass mixed me up as a kid. I heard "Heart and ass". — oops
- I used to think that when people had heart attacks someone came and stabbed their heartAnon
- I used to think that if you eat pig heart, you could grow another heart and be twice as healthier. Anon
- I thought the song "Party Time" by Moby was actually saying "heart attack" (this was before I knew the title)— Elviessa
- I used to believe an artichoke was an animal and we only ate its heart. — Laura
- I used to believe that only people that were in love had a heart.— Nikki