Halloween has long had a tradition of scary, but there is also a general consensus growing that its sexy too. We've all seen the barely-there sexy adult costumes around, and as Buffy said in Buffy the Vampire Slayer, "its come as you aren't night." Someone who is normally demure and innocent can totally pull out the sex. Just as someone who is usually a bit more in touch with their sexy wiles can innocent up, in their own sexy way.
I don't know about your neck of the woods, but in Denver every weekend all weekend there are sexy parties going on. Hallowfreakinween, Haunted Hotel, and the Victorian Fetish Ball to name a few.
The fun of mixing sex, naughty, and scary together is its own genre, Science Fiction Horror authors like Laurell K. Hamilton and Stephen King are know for blending the three in beautiful and terrifying ways.
Bringing horror, fantasy, and science fiction together in erotica is no new trick (Did you see Delilah Fawkes' Monster Sex Bundle?) but its a fun challenge for any erotic author to take a subject that was once chosen as horror and fright and make it sex and eroticism. Here are mine: