Crispin Glover on David Letterman Show, 1987

In this classic clip, a totally paranoid and confused Crispin Glover shows up on "Late Night with David Letterman" decked out in bell-bottom pants, platform shoes and a long-hair wig. After Glover challenges a visibly shaken Dave to arm wrestling and then nearly gives him a karate kick to the head, the show's producers wisely opt for a commercial and then escort Glover out of the studio. I've always thought Glover was promoting the bizarre film, Rubin & Ed, at the time - but that flick didn't come out until 1991. Apparently, Glover's Letterman appearance coincided with the release of River's Edge. Either way, it was pure brilliance and ranks up there with the performance art of Andy Kaufman.