John Stump's 1980 composition Faerie’s Aire and Death Waltz (from 'A Tribute to Zdenko G. Fibich') is a parody of a composition and not intended to be played — but someone did!
Of course, the Youtube version doesn't follow all the directions on the score — notable omissions include "release the penguins," "gradually become agitated," "duck," "remove valve," "optional shoehorn" and "remove cattle from stage."
(via Diane Duane)