The Conspiracy Of Beards singing "Chelsea Hotel #2" on the PATH train back to New York after they appeared at WFMU in Jersey City. Video shot on the fly by J Neo Marvin, who says it was pretty noisy, which is why it took a couple of lines for everybody to get going. At the end you can hear the conductor berate him for filming the moment: "You can't take pictures here!" Party-pooper.
Read more about it here.