New York slang for a man that all the girls want and all the men want to kick his ass.
"If I catch that Big Johnny with my woman again he's a dead mofo!"
A Big Johnny is when a girl is being gang-banged by two men; one penis in her mouth and the other in her vagina. If both men come simultaneously, she then pulls the penises out so that they ejaculate on each other's penises.
I was in a threesome once and we did a Big Johnny. My dick was sticky for three whole days.