Are You too Sexy for your Market?--veinglory

After reading
Karen's blog about twincest I began to wonder. Where are our squicks? I came across twincest, wincest and all sorts of -cests as Con-txt. (But seriously is fandom disappearing up its own jargon?). It didn't shock me much partly because there are sibling romance and/or sexual in fantasy books, in history and in recent times right here in America (e.g. see the nonfiction book
Farm Boys).
But we all have our squicks. Mine would be real rape and most types of unsafe sex in contemporaries. Others would probably draw the line in other places: smoking fetish, pregnancy fetish, bestiality, necrophilia? But I think the interesting thing is that almost any squick can be a good and necessary part of story if the story is written to require it. David Feintuch likes spanking, Diana Galaldon likes to work in some rape of a male... but they are good enough writers to take most mainstream readers along for the ride.
In erotic romance there seem to be two competing forces. One is the desire to read something a little salacious and daring, and the other is to not jump into the perv-pool with both feet. But now the genre has been around long enough that a book that is mainstream for some is pretty shocking for others. My question is, what taboo have you written about but left on the hard-drive--or thought about writing but not written because you think it might be a kink too far for the market? If there was too be an erotic romance anthology called
'Jumping into the Perv-Pool with Both Feet' what story would you submit?