Young Memphis star Ja Morant has been accused of "thuggin" on Twitter, despite being from a nice two-parent home.

Apparently, he also gets pretty aggressive in IRL.

A 17-year-old is suing Morant for roughing him up during a pickup basketball game that went down this summer at Morant's Tennessee home.

The teen claims that he and Morant got into a verbal altercation on the court and he threw the ball at Ja, accidentally hitting him in the face.  Then Morant walked up to him, put his chin on his shoulder, and asked a bystander "Should I do it to him?"

Morant followed that up with a closed-fist punch to the face and continued hitting him -- with the help of another man -- when he hit the ground.

The teen filed a police report, but no charges were filed after a month-long investigation.  Morant told police that the teen threatened to "light his house up" after the altercation, which put Morant and his family in fear.

Morant's team has yet to respond to the suit.