Filk
From ConRunner
Filk
A type of music often found at SF conventions, and now often the main subject of dedicated conventions (such as Contata, FilKONtario, Ohio Valley Filk Fest) as well. Fans were singing folk-songs at conventions quite early, and writing songs or adding new words to old tunes(parody) nearly as early.
The term "filk" originated as a typo in the title of Karen Anderson's article "An Introduction to Filk Singing" in 'West By One and By One', an anthology of Baker Street Irregular pieces published by Poul Anderson in 1961. Info from "An Egocentric and Convoluted History of 'Filk' and Filking", Lee Gold