Mystikal -- Watch Ya Self ... I'm Back in the Slammer

Rapper Mystikal -- famous for his 2000 hit "Shake Ya Ass" -- just checked into a Louisiana jail this morning, where he's expected to serve out the rest of a 90-day sentence for domestic abuse.

As we reported, Mystikal -- real name Michael Tyler -- was arrested in Baton Rouge on a domestic abuse charge back in February, and a judge ruled it was a violation of his probation. The circumstances surrounding the arrest are unclear.

Mystikal was put on 5-year probation following a 6-year prison stint for sexual battery and extortion.

Mystikal pled guilty in 2003 to forcing his hairstylist to perform oral sex on him.