A genre for fanfiction. If you know Mystery Science Theater, you have an idea. In a MSTing a fanfiction writer takes original characters and puts them into his own setting, where they have to read other fanfiction and comment on them. As this is not only plagiarism, but also a quite rude way to make fun of another writer, MSTings are only allowed, if you have permission from the author of the original fanfiction you are MSTing. Not everyone can laugh about himself.
'Oh god someone wrote a MSTing story about my fic! I'm so reporting them!'