As can be surmised from its title, the festive jingle isn't exactly safe for work.

As for the history behind the tune, the legendary rockers explain:

In 1987, the Midnight Riders were asked to participate in a children's charity Christmas album with their rock peers. The Riders refused. In a 1993 Guitar God Magazine article, Dusty explained: "Givin' kids charity just makes 'em weak, man. Teach a kid to fish, he can eat fish his whole life. Teach a kid NOT to fish, he starves to death. Where I come from that's murder, Homes." A few years later, the Riders grudgingly agreed to participate in a 1998 Christmas album in exchange for not having to do 30,000 hours of community service. "All I Want For Christmas is to Kick Your Ass" was written, recorded and mailed in less than one hour.

The seasonal wishes come on top of Left 4 Dead 2's recently released mod tools and support, with developer Valve planning to unleash a new downloadable campaign, which just so happens to feature the original Left 4 Dead crew, in the new year.