A general greeting, normally used between close friends as the phrase can come off as offensive. Two meanings, firstly as a merging of the two phrases how's it going and what's up, and secondly as a slightly perverted greeting much like how's it hanging
Hello friend, how's it up? Fancy a biscuit? OR, How's it up your Nanna, you filthy dog.
by Moe Liebelt August 09, 2006