Ken Casey, the bassist and singer for the punk band, took care of an unwanted stage occupant during a show at Terminal 5 in New York.

You can mosh, rush the stage, shout and stomp at a Dropkick Murphys concert, but the Boston rockers draw the line at flashing a Nazi salute.

Near the end of its March 13 show at Terminal 5 in Midtown Manhattan, the veteran Celtic punk band invited fans onstage -- as per tradition -- to participate in an encore rendition of "Kiss Me I'm Shitfaced." Fans continued to pour onto the stage as the group transitioned to another classic, the anti-white supremecist ditty "Skinhead on the MBTA," then a cover of AC/DC's "TNT."

That's when things got a little ugly.

According to several blogs -- and caught on video from the scene -- a large man with a shaved head began to flash the Nazi salute, with a bent arm shooting straight out from the chest. Founding bassist-singer Ken Casey moved toward the guy, shoved him aside and began a pile-on that ended half a minute later with a torn shirt and one less skinhead onstage.

He took back the microphone and screamed, "Nazis are not f---ing welcome at a Dropkick Murphys show!" and the crowd went wild.