His first publication, as a high-school student, was in MAD magazine. His books are full of jokes, both highly technical ones and more trivial ones. :-)

If you have some mathematical inclination and a couple of hours to spare, you may like watching his (1-hour) Christmas lecture from 2017: https://www.youtube.com/watch?v=BxQw4CdxLr8 — you may need to listen carefully (he's over 80 after all), but some of his humour comes through at moments.