(adjective phrase) having the intent to leave a place or situation quickly and promptly; comes from the phrase "I'm outtie" which sounds like "I'm Audi" from which follows "I'm Audi 5000" (as in the car) which eventually became simply "I'm five thousand." See also "outtie" and listen to the outro of "Straight Gangstaism" by the Geto Boys for an example.
"This party was cool, but now I got to go. Peace, I'm five thousand, y'all."
