"Yah mean?" is a slang term that originates from the second scene of Scary Movie 2. It can be used in almost all situations, especially those in which one is trying to be gangsta.
A rough translation of "Yah mean?" converts to:
"Do you comprehend the words in which I am saying?"
Yo, dat honey ova' dere looks fine, yah mean, son, yah mean, yah mean?