It's Joke

The broken Enghrish version of "jk".

Source

Fan Translation:"Mari: Watch me grope this girl's titties.""Dia: Aww what the hell? Man, fuck off Mari.""Mari: 'It's joke!'""Mari: 'SHINING!'""Dia: 'Bitch, I am going to slit you open and drain you like the pig you are.'""Mari: 'It's joke!'""Mari: 'This isn't a joke though, this school is flat broke.'""Dia: 'lul'""Mari: 'Look, you guys. You're finally popular'""Riko: 'It- It can't be!'""Chika: 'Finally, our time has come!'""Mari: 'It's joke!'""Chika: 'Never say 'it's joke' again for the rest of your life, please.'"Despite this depiction being fictitious, the use of "It's joke" generally will make you end up in a similar situation with similar responses.

Also do the voice too. it funee.