Here's a story about a no-legged man in an ass-kicking contest ... 

Ex-Olympic sprinter (turned convicted killer) Oscar Pistorius was involved in a prison fight in the South African penitentiary where he's locked up ... officials confirm. 

The Blade Runner -- who's serving a 13-year prison term for the 2013 shooting death of girlfriend Reeva Steenkamp -- got into the scrap on Dec. 6. 

Prison officials say Pistorius and another inmate fought "over the use of a public phone in the special care unit."

Pistorius only suffered a bruise. No word on the other inmate. 

Not so tough without your gun, are ya?