Herzog once promised to eat his shoe if a young American film student went out and actually made the film he was always only talking about. The young student was Errol Morris, who met the challenge with his off-beat 1978 pet cemetery documentary Gates of Heaven (1978) (and went on to make The Thin Blue Line (1988) and Fast, Cheap & Out of Control (1997)). Herzog makes good on his promise in the film Werner Herzog Eats His Shoe (1980), directed by Les Blank.
http://www.youtube.com/watch?v=rd6rUo7Htso