Chyeah = Ch + Yeah. It is a verb/adjective which decribes the level of awesomeness in a story someone tells. I have submitted it to the Urban Dictionary for approval as a colloquialism

How gangsta wanna-be's say "yeah" because they think they're cooler for it.

Something an annoying bitch will say when she agrees to something you have said.

the meaty part of a bone

another phrase used by that person with an IQ of however many cows they can count on a milk carton...

Or in other words... Yeah. Pronounced in a valley girl sort of way with lots of sass. Means yes (yeah, for sure. ) Said when replying to an obvious question or when agreeing with someone.