My brother was on this show. His stupid trick was to turn his eyelids inside out and roll his eyeballs so only white showed, all without using his hands.
I miss Letterman. Late night television died a horrible death when he retired. His last few years weren't that great but, even then, he was way better than that hump, Leno.
I remember watching a lot of David Letterman shows when my second son was born in 1983. During all the late night feedings, I'd have the David Letterman show on in the background. 💖