A childhood belief about songs

When I was little, my dad and I would watch Sesame Street together, and my dad would sing along to the songs. One day I asked him how come he knew the song, and he said he knew all of them - meaning he knew all the Sesame Street songs since we watched it so often. I, however, took that to mean that my dad knew every song ever made in the world. So I would ask him for lyrics to a song when I didn't know them, and my dad would go look them up if he didn't know them... So I decided that meant that he had a really big memory but it was too big to carry all of it around in his brain, so he would open his head and change the memory part of his brain.