East coast slang meaning, to beat something into submission, using full force, whether pulling, pushing, kicking or punching, but typically it involves a severe amount of punching, and a degree of punching where the subject ultimately stops resisting. This is typically a redneck term, and usually more of a taunt than an indication of something destined to happen in the very near future. Also used by hipsters as a throw-back joke among friends, meant to make them laugh at the memory of high-school bullies on the east coast.
"Shut the fuck up faggot or i'll fucking REEF ON YOU." usually the "faggot" is not gay, but simply progressive, or an outsider.
"Aw man, I was at this party last night and dumbass from Central High showed up. I fucking REEFED ON HIM, HARD."