The lyrics to Outkast's song "I'm sorry Miss Jackson"...I was convinced he was saying "It's my British accent". Never mind that the guy has NO trace of a British accent :-)
A childhood belief about misheard lyrics

others believed things like this
- I used to believe that anyone who wasn't British (as I am) thought of themselves as foreigners!— "velveire"
- I used to believe that a "No Loitering" sign was "No Littering", inexplicably spelled with a Brooklyn accent.— erin
- My younger sibling thought that Brittany was the name of the country where British people livedAnon
- I used to believe that if I spoke with whatever accent a language was in, I was speaking that language...— Renae
- i thaught the michael jackson song billy jean song said Janet's not my son Anon
- I watched a Michael Jackson music video with my brother, and we were convinced he was a woman.— Adrian