prangin out 

When your feeling high on coke. This is the name of one of Mike Skinners (The Streets) songs and he explains it here at this link.
The word chang means cocaine and prang means agitated or fear of something. So the combination of chang and prang is prangin. When your getting a buzz on cocaine.

Jimmy was prangin out last night before be passed out on the couch.

prangin out by Isaac LeMasters July 7, 2006

pranging out 

paranoia coming from a drug induced state. similar to tripping out.

I'm pranging out, there's voices talking to me.

pranging out by dashmi May 2, 2006