Treehorn Thug Was A Dude

The Dude meets Dude...

The blonde Treehorn thug, who micturates upon the Dude's rug at the beginning of the movie and thus gets the ball rolling, so to speak, is played by Mark Pellegrino.

Pellegrino is a hard-working B-list actor, mainly appearing in TV series (most recently in Dexter) rather than in movies, in which he usually plays minor roles (e.g. 'tourist #6' in Jurassic Park). In 1989, 9 years before soiling the rug that really tied the Dude's room together, Pellegrino played a guest role in the series Doogie Howser, M.D. He was credited only as... Dude.