You know what's one of the best Shower Singing Songs ever? That song by The Smashing Pumpkins (which might possibly be called Rocket or something) that goes "I used to beeee a leeetle boyeeee."

I like this song.

When I sing it in the shower, I sing it in the voice of Sniffles the Mouse from the Merrie Melodies cartoons of my youth. If you are unfamiliar with the work of Sniffles The Mouse, you may sing it in the voice of Scooby and/or Scrappy Doo.