Jacking rack - v. - Anything that can cause you to fuck up the good thing you have going. i.e. parole, being at a good joint, etc. Example, ". . .I know he only got me for one soup, I should just let it go but I swear to God if he even talks to me I'll jack rack beating the brakes off that cat."
I'm not sure on the etymology of the word, but I'd assume it would be pertaining to jacking off your rack, just like out on the streets if you did something stupid you'd say, "I really jacked that off." Or maybe you wouldn't, depending on how classy you is. The "rack" would pertain to the thing you perceive as valuable. Your "rack" is your bed.
Beating the Brakes Off - phrase - This is a term used when describing how bad you're going to kick the shit out of someone. I have no idea what it really means but I love this one. I use it all the time even on the streets. Maybe it has to do with how hard you have to beat old drum brakes to get them to break loose.
Press Your Bunk - phrase - Something you would direct the person that your are going to beat the brakes off of to do. You're essentially telling him to go lay down somewhere and shut up. Example, "You better press your bunk before I come over there and beat the brakes off you." Usually followed with "bitch ass" and a cool walk-away walk.