a way of showing disrespect to another male. "beef" being slang for (pause) male genetalia, "rock beef" is essentially telling someone to "suck a dick" or "fuck off"
rock beef
When a GF or wife requires their man to stick both their thumbs up their own butt, jump up and down, and 'hee-haw' like a donkey in exchange for permission to have a night out with the guys. "Rocking the Beef" is believed to have originated when George Washington wanted to go meet the guys, eat wings and sign the constitution, but Martha wanted him to stay home and watch "This Is Us" on NBC. For the sake of national freedom George agreed to "Rock the Beef".
"FRIEND 1: Did MJ confirm with you that we're getting wings tonight? He didn't answer my text. FRIEND 2: He said he was free, but he may have to Rock the Beef first"