In my verse, I had them running afoul of a Spanking Demon. It's not that far-fetched, considering some of the other creatures Buffy and the Scooby Gang had to face. I can only imagine how Joss Whedon, the creative force behind Buffy, would have written it.
I can just see the aftermath now:
SCENE--INTERIOR, BUFFY'S HOUSE, THE KITCHEN
(The back door opens and the gang starts to file in. They are all carrying weapons, which they place upon the kitchen counter upon entering. Buffy enters first. She is carrying an axe in one hand, and with her free hand is gingerly rubbing her bottom)
BUFFY: A Spanking Demon. Who knew?
(Willow enters next. She, too, is rubbing her backside)
WILLOW: The ten arms should have been a giveaway.
(Cordelia enters. Her hands are tenderly massaging her derriere)
CORDELIA: Not to mention the five laps!
(Next in is Xander, the lone male of the group. He, too, is rubbing his butt)
XANDER: I think I speak for all of us when I say we will never talk about this again! Ever!
(Anya is the last in. She, however, is briskly rubbing her bottom and has a huge smile on her face)
ANYA: Personally, I found it exciting! And by exciting, I mean...
(Xander spins towards Anya, pointing)
ANYA: Okay, Mr. Grumpy Pants. Geez!
(Anya starts to leave the kitchen, but stops next to Buffy, Willow, and Cordelia)
ANYA: Funny, he's never complained about it before......
(Anya exits, the other girls smile and try to refrain from laughing out loud while Xander looks like he wishes the floor would open up and swallow him as we.....)
fade to black
Here is the very spankable cast:
(photos: Sarah Michelle Gellar from "Cosmopolitan" magazine; Alyson Hannigan from Egotastic.com; Charisma Carpenter and Emma Caulfield from "FHM" magazine.)