She was lookin' kinda dumb
With her finger and her thumb
In the shape of an elf on her forehead

The story:

For my entire childhood, I had been singing about the elf on her
forehead and wondering how in the world a person would
accurately and recognizably form an elf using just their finger and
their thumb, when one day I was singing along and my mom started
laughing at me, and goes "you know it's L, not elf, right?"