Howyewdewin' is a colloquial way of saying How are You Doing?. It is used predominately in the northeastern United States, mostly around New York, New Jersey and parts of Philadelphia. The term gained nationwide popularity from the TV Sit-Com, "Friends". Character "Joey", used the term to greet his "Friends"
You see somebody from back on the block, you say "Howyewdewin'?" Now, current tradition dictates that the only correct answer to "Howyewdewin'" is "No, Howyewdewin'?". This can escalate a few levels. The conversation can continue to go back in forth in proportion to the stubborness of both parties. The only thing that can de-escalate and render it inert, is a hug