Well, since you seem unable to Google, I will help you. The phrase was originally penned by a BLACK journalist for a (if I remember correctly) San Francisco newpaper. A popular conservative, musical satirist then created a song inspired by the article. Limbaugh agreed to play it on his radio show.
I'm certain you will acknowledge this and apologize for spreading lies in order to advance a political agenda.
Lighten up. It's an honest mistake. He uses it so much, it's easy to attribute directly to him. He just didn't conjure it.