I thought the Beach Boys song went 'Wouldn't it be nice if we were older, then we wouldn't have to wear a thong.' I sang it once while showering at a hotel and a whole line of people told me in the breakfast room the right lyrics. I still think mine are better.
A childhood belief about misheard lyrics

others believed things like this
- One kid I know believed that because I wear glasses, it wouldn't hurt if he poked my eye.Anon
- I wouldn't wear stripy socks because I used to believe the stripes dug into your feet— Shirley Reeves
- I used to believe in the Cysco song "Let me see your thong" he said let me see your thumb.— Anymous
- i thought I got one year older when my family sang the birthday song.— I am the ghost
- When I was little I thought grown ups could fly but wouldn't tell me about it or teach me until I got older.— James the Great
- I once thought a vent in my hotel room led down to the center of the earth.— flarn2006