AC/DC's "Dirty Deeds (Done Dirty Cheap)" -- I always thought it was "Dirty Ds and the Thunder Chief".
Bob Dylan's "Blowing in the Wind" -- for some reason I thought Bob was singing, "The ants, my friend, the ants are blowing in the wind". Hmm..
A childhood belief about misheard lyrics

others believed things like this
- when i was younger i thought ac/dc's dirty deeds (done dirt cheap), was dirty knees and the thunder cheeks.— S
- a friend thought that the song "dirty deeds done dirt cheap" was saying "dirty deeds dunderchief"— dubs
- i used to believe that if i looked at trees, the wind would start blowing. Anon
- When I was little, I thought that Water Towers were full of dirty laundry. Why? I dont know.Anon
- When I was younger, I thought my brother kept eating my dirty socks, and that's why his feet smelled.— Kail
- I used to believe that toilets would open and swallow you up because they got dirty!!— swallowing toilet