when i was a little kid in primary school we would have to sing the Australian national anthem at assembly every Monday morning.
I guess they didn't do such a great job with teaching us the words, because until the age of 10 i was absolutely convinced that the line "Australians, all let us rejoice" was actually "Australians all love ostriches". As a child I didn't even think it odd enough to question why we were all professing our love for a native African bird every week.
A childhood belief about misheard lyrics

others believed things like this
- I am Canadian and when I was little I would sing "True Pastry Love" instead of 'True Patriot Love"— Jess
- I thought that if you had sex with a man that didn't really love you, he would be able to pee in you— Lenny
- I always hear Manic Street Preachers 'You Love Us' as 'You Love Arse'.— Lou
- I believed that dolls could feel when I didn't love them, that's why I treated them well.Anon
- I used to believe that the B-52's song "Love Shack" was actually "Love Shark!"— Natalie
- When Madonna sang "let the choir sing" in "Like a Prayer", I thought she was singing "love by proxy"— Kristen