Everyone loves a good board game, but Taboo isn't all that taboo, Risk is anything but risque, and Sorry! isn't even about dudes who didn't pull out. For a game that truly brings the inappropriateness: Cards Against Humanity.
Described as "a party game for horrible people" by a group of suburban Chi high school buddies who first developed it for a NYE party, CAH's somewhat reminiscent of Apples to Apples, but's designed to cross just about every conceivable line, so it's definitely hard core. The game consists of a plethora of Answer Cards -- doled out in groups of 10 -- which players take turns laying down in an attempt to create the most hilarious phrase in relation to a fill-in-the-blank Question Card, with the individual who chose said Question Card (aka the Card Czar) responsible for rewarding the best response with an Awesome Point (not to be confused with an Awesome Blossom Point, as those are either cholesterol or Mayim Bialik's nose). For example, Q cards such as "Why Am I Sticky?", or "BILLY MAYS HERE FOR ____" might yield responses including ethnic cleansing; pre-teens; Stephen Hawking talking dirty; passable transvestites; necrophilia; and Harry Potter erotica, which like necrophilia, involves a lot of Death Eaters.
Currently they're offering free PDFs containing the game cards (along with instructions on how to how to print them out/customize answers), or you can opt to pre-order one of the pro-made packs now in production for just $15, assuming of, course, the $5 shipping fee doesn't make you want to pull out.