Correction Appended

LAST November, William Graham was minding his own business on karaoke night at a sports bar near his home in Miami when things took a nasty turn. On the other side of the bar, he recalled, a drunk couple was arguing. The woman gave Mr. Graham a look, which her boyfriend apparently didn’t appreciate. He approached Mr. Graham, 44, flicked a cigarette at him and challenged him to a fight.

Unfortunately for the aggressor, Mr. Graham is a passionate student of the art — scratch that — the act of street fighting. He owns approximately 20 DVD’s and books on street fighting, many of them by the brawling guru Paul Vunak. One is perfectly suited for karaoke nights that get out of hand: “Anatomy of a Street Fight.”

Mr. Graham recalled his training, and what happened next at the bar was not pretty. He first went in with his thumbs for an eye gouge before letting loose with a “straight blast,” a flurry of driving blows to the midsection (“Bruce Lee’s favorite,” Mr. Graham said). The aggressor fell to the floor, at which point Mr. Graham applied a choke hold until security separated and dismissed the two — through separate doors. The whole episode lasted less than 20 seconds, Mr. Graham said. In the end, the aggressor was vanquished and Mr. Graham’s manhood was intact, just as his videos had promised.

His opponent was in a state of disbelief after the fight, Mr. Graham said. “He thought we were going to do the whole boxing match thing. He wasn’t ready for a poke in the eye and a 50-yard dash down the centerline.”