I have two:
I thought "I'll write a symphony just for you and me" in Elton John's 'Are You Ready For Love' was "I'll ride a cell phone in, just for you and me".
Also, I thought "Sometimes I wish someone out there will find me" in 'Boulevard of Broken Dreams' by Green Day was "Sometimes I wish someone will pillow fight me"!
A childhood belief about misheard lyrics

others believed things like this
- As a child, I thought that Olivia Newton-John was Elton John's wife and Juice Newton's sister.— Connie
- As a child I used to think that Olivia Newton-John and Elton John were married.
Boy, I was way off.— Lisa - Yep I thought the Zephyr song was fly away on my cell phone— Jenny
- i thought in elton john's "tiny dancer'' the chorus was "hold me closer tony danza"— d.a.
- I used to think the lyrics to Elton John's Tiny Dancer were "hold me closer Tony Danza."— kstawitz
- My friend used to believe that the lyrics to Elton John's "Tiny Dancer" were:
"Hold me closer Tony Danza"— I'm with stupid