A former "Real World: Las Vegas" star learned the hard way NOT to put his hand up a girl's skirt (allegedly) ... after it landed him in the back of a cop car, pepper-sprayed to the nines.
Dustin Zito -- known as the 2011 housemate who did gay porn -- was arrested Saturday night, outside a bar in Louisiana. Cops say Zito allegedly tried to reach up a woman's skirt and touch her inappropriately. The woman reported the incident to police.
But it didn't end there ... cops say when they showed up, Zito violently resisted the arrest. So they used pepper spray to subdue him and take him into custody. Ouch.
He was charged with sexual battery and resisting an officer violently.
Zito remains in jail. A court date is set for July 16th.