Jason Sparks, 37, was arrested and charged with aggravated assault for the weekend stabbing of his cousin, The (Columbia) State reported.
Police said Sparks, the unidentified victim, and another unnamed man were watching an MMA fight on pay-per-view when Sparks and the other man started faux fighting.
"Three individuals were watching MMA, at which point two men got into a play match," Richland County Sheriff's Department spokesman Curtis Wilson said. "These individuals had been drinking prior to the incident."
Sparks lost the play match and his cousin tried to head off any further fighting.
"The suspect then accused his cousin of going against his own family, pulled out a pocket knife with which he then cut the victim in the upper body," Wilson said.
Then, while Sparks and his girlfriend were taking the victim to the hospital, the suspect allegedly assaulted the victim again "before passing out in the back seat," Wilson said.
When deputies arrived at the hospital, they arrested Sparks, Wilson said.