I've heard two new-to-me slang expressions in the past week, love them both, and plan on incorporating them to my speech to the extent I am able. They are:
To Do the Swirl: When a black person and a white person have sex they "do the swirl." I didn't understand it until I thought about it for half a second, then laughed hysterically and wondered how that term hadn't become widespread long ago.
Yatter: A person with a strong New Orleans accent. It comes from the expression "where y'at?" which is how the expression "where are you at?," meaning, roughly, "what's up?" A Yatter (or, occasionally, Yat) is somebody whose New Orleans accent is so pronounced that more mainstream New Orleanians make fun of them for it.