A greeting pronounced 'whu-chang-maw' in a slightly nasally tone with a lot of gangster spice. Mostly used by white people trying to act like a baller shot caller. It can mean, "what's up bro?" or similarly, "what's good friend?" Appropriate at all social gatherings of cool people.
Ryan: Wha Chang Ma!
Kevin: I'm just making a potatoe launcher dude, come help me!