It's hard to write a tune with bit-off fingers

The story:

A friend of mine lent me a few of his CDs of music from the 70s, and one was an album by Elton John. I'd heard some of the songs before, but not this one. I listened to it a few times in the car without ever looking at the song's title, and I was convinced he was singing "It's hard to write a tune with bit-off fingers", which I took to mean biting your fingernails a lot with anxiety. But it still struck me a little odd. I finally checked the song's title and when I realized the mistake, I couldn't stop laughing. The misheard lyrics I thought were so deep now seemed so funny.