Used commonly on discord. J4J Stands for Join 4 Join where you join the server someone sent you and he/she needs to join your server.
Discord User 1: J4J?

Discord User 2: Sure, send me your server!!
by GamerSheep6000 December 23, 2019
Justice for Juntow

A phrase commonly used on the game Pkhonor, referring to the banning of a player because of their skin color.
"I hope Juntow stays banned because whenever I yell #J4J this underdog player does a big drop party"
by Dr Katwa June 30, 2021
Its most known on Discord as Join for Join
Hey lets do j4j(Join 4 Join)
by Vilendro April 30, 2019
mostly used on discord where you take turns telling jokes to insult each other.
Person 1: You a bitch run my j4j

Person 2: bet join vc

Person 1: Your mom so fat

Person 2: Your dad so fat
by sylix August 17, 2021