My wife says "What's shakin', bacon?" I have not heard anyone else say this, but it wouldn't surprise me if someone once upon a time said it on a television show or something like that. The list of these very informal ways of saying "How are you?" goes on forever. Here are a few more. What's up? (and therefore "Wassup?") What's happening? What's new? (And "What's new in your shop?" in a work setting - "shop" is slang for "office" not "factory") What's hanging? What's going on with you? (and therefore "What's going on whichoo"?) Of course, all you really need is "How are you?" I hope that helps.

Never heard that. But it's just a creative variant of what's happening, what's up, what's going on, etc. Don't spend too much time on it.

It is an older term that is not as popular today. But it means "what's new?" Yea it is colloquial and a conversation starter as you said.