The Inappropriate Elf Challenge
|Name:||The Inappropriate Elf Challenge|
|URL:||Elves! Elves! Elves!, Archived version|
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The challenge was based on the common trope in fanfic to make one half of a slash pairing--generally the shorter, thinner, more willowy partner; bonus points if he had pointy ears--into an elf, or otherwise transpose a SF, cop show, or other non-magical universe into a fantasy universe (probably because so many fans like fantasy.)
The archtypical elf AU has one of the characters revealing to their beloved that they are, in fact, an elf who has concealed their true nature. (This trope seems to have been particularly common in The Professionals fandom, but many unlikely fandoms have at least one elf story somewhere.)
This elf or fantasy au was frequently parodied. 
The Inappropriate Elf Challenge invited participants to write stories for fandoms where such stories were either a) not common or b) a really terrible idea.
Speranza kicked off the challenge with a vignette in which the hard drinking and swearing punk rocker Joe Dick from Hard Core Logo turned out to be an elf. Other notable Inappropriate Elves included the West Wing's Jed Bartlet, Homicide's Tim "Tym" Bayliss, "Scule'lye" from the X-files, Jeeves from Wodehouse, and the rapper Eminem.
The name of the challenge--"Inappropriate Elf"--leaves unclear whether or not elves were ever appropriate in the non-fantasy fandoms in which they have more commonly appeared. In any case, elf stories continue to be written; for instance, there are several featuring SGA's John Sheppard, played by suspiciously pointed-eared actor Joe Flanigan.