Human juke box

This afternoon I went to change into some different clothes and immediately got a song from the Brady Bunch in my head.

"When it's time to change you've got to rearrange"

At least I think it's from the Brady Bunch.

Sha-na-na-na-na-na-na-na-na!
Sha-na-na-na-na!

When it rains I usually get:

"Raindrops keep falling on my head"

Why can't they be cooler songs? Why does my brain go for the super corny songs? (Sometimes with extra cheese...)