'I Used to Eff Guys Like You In Prison!'

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Insanity in the men's room at the Russell Athletic Bowl on Wednesday -- when a 1-legged West Virginia fan got punched by a Miami fan ... and then screamed, "I used to f**k guys like you in prison!"

While the Mountaineers were taking on the Hurricanes in Orlando ... the two rival fans got into a heated argument at the urinal.

The WVU fan threatened to pee on the UM guy ... the UM guy punched the WVU fan in the face.

A chase ensues -- and that's when the WVU fans drops the prison line.