Merkin \MUR-kuhn\ , noun;
1. False hair for the female pudenda (aka: crotch wig)
I was listening to public radio today when I heard them talk about the Merkin Concert Hall at the Kaufman Center. I almost fell out of my chair because in my (apparently uncultured) mind merkin means only one thing. Maybe I should stop listening to Bob and Tom and start going to philharmonic concerts. Maybe not.
The origin of merkin is unknown, but it may be a variation of malkin ("a slattern, woman of the lower class," later "mop"). Merkin is first attested in the 1530's with the meaning "female pudenda" from the "mop" sense of malkin. In the early 1600's the meaning changed to meaning "artificial vagina" or "counterfeit hair for a woman's privy parts." Use of that 'counterfeit hair' by prostitutes dates to the mid-15th century. Ladies of the night would use the fake hair to cover the fact that their hair was lacking due to venereal disease or shaved to get ride of body lice.
In modern times the merkin is still in regular use, though not necessarily by prostitutes. They are common in Hollywood to avoid accidental 'full-frontal' nudity and to add hair if it's needed for historical accuracy. Decorative pieces are used, often in conjunction with nipple tassels or pasties, as part of a burlesque costume or applied to fake vaginas.
Apparently merkin is also common internet slang for American, which comes from a European slang term that dates to the 1960's. We can thank certain accents, particularly that of President Lyndon B. Johnson, and their pronunciation of American for that one.