I've posted a few in the past, and here's one more. It's from The Tonight Show in 1973. The video ends abruptly, but it's near the end.
By the way, at one point, his album Comedy Minus One get mentioned. This is a remarkable work -- not for everyone (indeed most of his work isn't for everyone), but it's the most unorthodox comedy album you're likely to hear. The first side of the LP is normal, and very funny, including perhaps my favorite of his bits, "Rewriting the National Anthem." But it's the second side that's...well, unique. It's a long sketch -- the full side, probably about 20 minutes long, as I recall, in which one part is left out. Inside the album cover is the dialogue for the sketch -- with that "missing" part, and you the listener are supposed to read it...and be part of the sketch! So, yes, that's what I mean about "unorthodox," "unique" and "not for everyone." But I love the guy.