Why are there so many songs about rainbows?

The balding man mistook an actual rainbow for the band Rainbow.

George Kostanza drew a picture of a rock and roll dude while watching a balloon with a red cross symbol fly over a big rainbow in the sky.

Homer Simpson had grown rounder over the years; the growth of a tail perturbed him. Still, he continued painting inflamed penises for the Red Cross's circumcision awareness posters. Someday, everyone would be as happy as him.

Homer Simpson reverts to his morbidly obese stage, grows a monkey tail, and takes up painting.