“Maji-kichi” means “seriously crazy”…
The term originated on the 2ch message boards and evolved from there.
The term is short for 「マジでキチガイじみてるからやめろ」(Majide kichigai jimiteru kara yamero) .
The literal translation is “Stop doing that because it’s oozing craziness.”
Over time and use, the phrase was shortened into the current Maji-kichi (seriously crazy).
Basically, you use it on people you think are F%#$’in out of their mind…wwww
It can be used on really crazy people as well as on your girlfriend or boyfriend.
Maji-kichi…now you know.