Here's a very simple challenge for you for Halloween. It was made for the SUnnydale Writers but why not post it here and see if any on my Flist wants to play. I'm not one for complicated challenges with lots of things you have to have in it so I'll make it simple:
1) it can be BtVS, AtS or both
2) Any time period you want
3) any kind of ship or NO ship for those of us who prefer action to romance
4) it can be Halloween or Samhain
5) set it anywhere, California or otherwise.
the only must haves:
1) someone has to be in costume (I don't care who. If you want to have Principal Synder in costume for the school party, go for it, Fred and Cordy trying to cajole the boys into dressing up and having kids into the Hyperion, go nuts)
2) someone has to be questioning an alcoholic drink choice of a friend. Since a lot of us aren't drinkers here's a very helpful link
http://www.webtender.com/ just go to browse and I suggest that you browse by name you'll find PLENTY of things you can't believe people would drink (and no pop ups)
That's it (oh if you decide on a historical fic you can bend the two must haves a little. I know a lot of historic drinks but I'm not sure when exactly American's started dressing up for Halloween. If you're setting the story elsewhere, keep in mind not everyone dresses up for Halloween so people might be looking at the characters funny)
If you decide to give it a whirl, just post it in your journal on Halloween. Have fun