David Shusters

Rachel Maddow on Friday played a video of a man in underwear banging his genitals against another man's forehead in a gay bar.

This was done to explain to her MSNBC audience the derivation of the term "teabagger," the sexually-charged double entendre that sadly became popular this spring and summer as Tea Parties swept the nation.

According to Maddow, "This is where "teabag" comes from. This is a clip from a 1998 film by John Waters that`s called 'Pecker.'"

As the dancer in the fictional gay bar squats to bang his genitals against a customer's forehead, the emcee played by Martha Plimpton says, "Hey, Larry, no teabagging. You know the rules. No balls on foreheads."

At least Maddow warned her viewers to "get the kids out of this room or put them in ear muffs and cover up their eyes" before she rolled the clip (video embedded below the fold with transcript, relevant section at 2:30, file photo):