Jason London -- Wife Sick of His Crap ... Files For Separation

Jason London -- the star of "Dazed and Confused" but possibly even more famous for sharting himself in a cop car -- is now on the receiving end of a legal separation.

Jason's wife, Sofia Karstens, has filed legal docs -- obtained by TMZ -- in which she seeks to split up their marriage of 2 1/2 years.

The papers don't reveal any reason -- other than irreconcilable differences -- but it could have something to do with his arrest last year in Arizona, after allegedly getting into a bar fight, getting arrested, hurling homophobic slurs at the cops and then defiantly crapping his pants in the back of the squad car.

Jason pled guilty last month to disorderly conduct.