The MYSTIC RIVER star became enraged when the pair - also responsible for animated TV series SOUTH PARK - jokingly encouraged Americans not to vote. Penn then fired off his letter, which he ended with the words "f**k off".
The 44-year-old actor's anti-war views are parodied in the film, but Penn claims not to be bothered by this.
He explains, "I just saw a guy who told people not to vote and I thought it was stupid."
Stone and Parker have previously expressed their satisfaction at the publicity Penn's outburst afforded their movie.28/10/2004 17:35