Once again, you're at work. Maybe you are returning from your trip to the coffee machine or perhaps you went over to accounting to yap for a few moments and you figure people might start wondering where you are so you dart back to your desk. Either way, in the hallway, you approach him. He gets closer and you prepare your greeting for him. You have a few options, but you decide to ask, "How you doin'?"
However, this is the guy who never listens to those short passing questions in the hallway and just replies blankly with, "Not much."
Now, this ain't a backbreaker. It's actually such an easy question to answer that most people just come back with the standard "fine" because you're not intended to think about it too much. Just say something, but make sure you actually answer the right question.
The other instance of this that you'll find in many office settings is this:
j3: "What's up, Bobby?"
Crap! That's not what I asked. I'm clearly asking for a verb or maybe even a noun, but you can't answer that question with an adjective! I'm not asking for a cure for cancer or a stock report, I'm just asking, "What are you up to?" If you don't think you're fit to answer than just mumble, pick your panties out of your butt and keep on walking.
So remember, the standard answer to "How you doin'?" or "How's it goin'?" is the word "Fine," which, not all too coincidently also means "end." You're done answering with one word. You can also hit 'em back with the following: slendid, fantastic, crappy, horrible or good.
And a proper answer to, "What's up?" is "Nothin." You can venture outside of that with really what's up, but remember, the key is to keep it short or else you'll be that other guy.