Brasklapp

Now that's hardcore! The only filk song I know based on one of these is Don't Bite the Sun (ttto "The Sign" by Ace of Base)..

I've seen a filk song based on Ancillary Justice, and Gary's filkindex gives me also two based on Gate of Ivrel and Frankenstein. Bit further than that, I don't know, but I'm sure there is several more.