I used to think that the songs "Have you Ever Seen the Rain" and "Who'll Stop the Rain" by Creedence Clearwater actually stated "have you ever seen Lorraine?" and "Who'll stop Lorraine?" I could never figure out why they'd write (not one, but TWO!) songs after some lady named Lorraine. Seemed kind of boring to me.
A childhood belief about misheard lyrics

others believed things like this
- My dad thought when he was little, rain was caused by army guys in the clouds with rain guns. — Daughter of the Weird
- I used to believe I could control the weather by singing rain rain go away or blowing the clouds away.— Shannon
- I believed that the rain would melt everything...I was terrified to go outside in the rain! — Cris
- I used to believe that one of Lady Gaga´s songs goes "bedroom ants" instead of "bad romance"— Anon the III.
- I used to think that Rain Man had something to do with Singin' in the Rain.Anon
- I thought if 3 cards stopped at a 3-way stop sign then they had to stop forever until Christmas.Anon