Dropkick Murphys Beat Down Nazi Concertgoer at New York Show (VIDEO)

A common sight at a Dropkick Murphys show is dozens of skinheads piling onto the stage when the Irish punk band plays their song "Skinhead on the M.B.T.A."

The tune is an ode to the working-class punks of Boston and NOT the stereotypical racist baldheads -- and singer/bassist Ken Casey reminded fans of that last week when he punched out a concertgoer doing the Nazi salute in the middle of a song.

Thanks to a few fan videos that have gone viral, we can all enjoy Casey's Irish vengeance. Here's a firsthand account, courtesy of Rocks Off (via Gawker):

"As the band kicked into T.N.T. by AC/DC some moron started seig heiling (the nazi salute) in time to the beat.

"Ken Casey noticed this and ran right over to the guy, smashed him in the face, took off his bass and hit him with that and then jumped on him and all out chaos ensued. We could only assume from our vantage point that said nazi got his ass kicked. About 30 seconds later Ken emerged from the pileup with his shirt torn and made his way back to the front of the stage. He strapped on his bass and said into the microphone 'Nazis are NOT FUCKING WELCOME at a Dropkick Murphys show.'"

Bravo, Ken. If you're now a fan of the band, they're out on the road touring behind their latest album, Signed and Sealed in Blood, which is a reference to tattoos, not any sort of Nazi pact.