look up any word, like hipster:
 
1.
one. a common phrase inserted randomly in conversation to add flavor.

two. a greeting meaning "wusssup?" or "how you doin'?" but in most cases no answer is required.
three. the verbal form of a fist pump.

note: not literally asking about a baby.
Example one:
"Hey, what's up?"
"No, I think you meant to say, 'how YO baby?'"

Example two:
George: "How yo baby?"
Cindy: *SLAP*
George: "HEY! It's a form of greeting!"
by Martha Weasley March 05, 2010