An instance of an individual, particularly a young, rowdy and unsupervised children, cause chaos, destruction, and potentially vandalism, in a public place. Primarily, the place in question is some form of general or retail store.
"Boy, we've got a Jit Going Hamin the Dollar Store".
—The cameraman in the infamous YouTube video "Kid Destroys Dollar Store", as he records the destruction caused by said kid.
jit means that guy or dude or bro. And Trippin mean you said or did something crazy. Nah in this sentence mans in awe. Combine the words, and you get nah jit Trippin