Jason London -- Sharting Conviction Wiped Clean from Record

Jason London can now say he was never convicted of crapping in a police car ... even though he pled guilty ... TMZ has learned.

Jason had pled guilty to disorderly conduct -- for sharting in a squad car after getting popped for a drunken bar fight in Scottsdale, AZ.

According to the plea deal he struck, Jason was required to complete a 16 hour alcohol-ed course. Once classes were completed, the judge agreed to erase the conviction -- as if it never occurred.

Well Jason graduated magnum cum laude from his class ... so it's like he never crapped in the car.