American slang for an upscale preppy/yuppie bar or tavern usually decorated with ferns as well as fixtures and furniture such as retro sofas and fake Tiffany lamps. They were popular meeting places for young singles. The phrase came into common use in the late 1970s and early 1980s.
The new pub has a nice cocktail selection but an unfortunate fern bar atmosphere.
N. /fuhrn-bar/ Drinking establishment frequented by gay men. (history - back when being a "gay bar" was grounds for having a brick thrown through your window, many non-breeder freindly establishments would place ferns in the window)
Bruce got a blowie from seth in the back room of "secrets" his favorite fern bar.