(2) a southern term for jug(s) or junkie(s) (same thing)
(3) (j) a jumpshot
(4) another word for joint(s)
(2) Matt: You mess with coke? Mark: Yeah. Matt:.... Fuckin J
(3) Dang Carmelo has a pretty jumpshot
(4) How many j's are you going to roll up?
Your friend will get mad if you say, "you're being a douche."
But if you say, "you're being a douche, js." it's more like your informing him rather than insulting him, in a lighter tone.