When I was young, I thought that in "Chapel Of Love" by The Dixie Cups they said "Going to the jack-a-lantern, Gonna to get married" instead of "Going to the chapel, And we're gonna get married".
I used to think it was a hallowe'en song, and wondered why I never heard it on October 31st.
A childhood belief about misheard lyrics

others believed things like this
- i used to believe nuns were married to jesus and priests were married to mary.— sunshine
- When I was young I thought that Jim Carrey and Mariah Carey were married because they had the same last name.— Aeris
- When I was very young, I thought that God was married to Mother Nature, and that together they made weather.Anon
- when i was young i believed that gay men got married to gay women!— robster
- I thought all teachers in school were married to each otherAnon
- I thought that to get married, your spouse had to have the same eye color as you did.Anon