A pet name for a gay man whose penis has a curve, or the curved penis of a gay man.
I'm the luckiest man on the planet. I hope you have a pot of gold for me at the end of that rainbow my little leprachaun. Daddy has some canola oil, let's see what we can do with those lucky charms.
A slut.
A person who is easy to get, who unabashedly throws themselves at another, or who puts on a slutty act.
(Not overly offensive, often used among friends.)
She does every guy she meets. She's such a rainbow!
Oh, my God, I can't believe the way you dance; you're such a rainbow!