There will be Filking 101 (an introductory panel) on Friday after opening ceremonies...and then open filking (performance) on Friday and Saturday night.
The most frequent mode of open filking at Icon is to form a loose Bardic circle and PICK, PASS, OR PLAY: Pick a song you want to hear, pass if you don't have anything, or whip out your (MUSICAL) instrument and give us a tune. Play also applies if you want to sing and don't have a musical instrument. Also heard as Pick, pass, or perform.
An excellent glossary of the language of filk can be found here.
Definitions of filk
As Debbie Ridpath Ohi's compilation What Is Filk? and the Interfilk What Is Filk? page each demonstrate, there is no consensus definition of filk, though one could divide the different proposed definitions by their focus on the content and style of filk music or the cultural aspects of filking as an activity.
One definition is based on filk as a genre: filk is folk music, usually with a science fiction or fantasy theme. But this definition is not exact. Filkers have been known to write filk songs about a variety of topics, including but not limited to tangentially-related topics such as computers and cats. And other filkers. Recursive "filks" about filks are common.
The other common definition is anthropological (and recursive): Filk is what is sung or performed by the network of people who originally gathered to sing at science fiction/fantasy conventions. Yet another definition focuses on filking as a community of those interested in filk music and who form part of the social network self-identified with filking.
Whichever definition one chooses, filk is a form of music created from within science fiction & fantasy fandom, often performed late at night at science fiction conventions. And whichever definition one chooses, the boundaries of filking are muddy. For example, filking overlaps with the singing and music performed by participants in the Society for Creative Anachronism or at LARPs.
credit to: http://en.wikipedia.org/wiki/Filk_music
"Plangerism is stealing from one source, research is stealing from many."