I know there are a lot of prince fans lurking about these parts. Quiet surprising story. It would seem the Purple One's favorite color was not purple.
http://www.stereogum.com/1960103/princes-sister-says-his-favorite-color-was-actually-orange/news/?utm_source=share-tw&utm_medium=button
It's nice to catch the occasional shocking news that isn't also terrible or sad. Next they're going to tell us J Mascis' favorite color isn't purple.
He probably figured purple rain made for a catchy lyric, and then ran with the theme.
IIRC, Lemmy said once that he preferred one armed bandits to poker, but that it was harder to write a song about spinning fruit. (_Ace Of Spades_)