SNL may have had Chevy Chase back at the “Weekend Update” news desk last weekend, but audience members at the Comedy Cellar got even rarer treats late Saturday night as both Robin Williams and Dave Chappelle dropped in for unannounced performances at the city’s top comedy club.

That’s Chappelle at about 1:53 a.m. Sunday, doing his thing. Note to self: Get a new phone. And to think, I’d just told Estee earlier that night that I always forget to bring my digital camera when things like this happen. (Bonus comedy nerd points if you know whose head that is in the lower left-hand corner of my photo)

Williams, shooting the film “Old Dogs” with John Travolta in Connecticut, performed a raunchy 20-minute routine just before midnight Saturday, complete with his trademark riffing and voices. But after joking about Lindsay Lohan, he got candid about his own recovery from alcoholism, telling the audience that “you realize that life is a precious thing” and telling comedians afterward that stand-up comedy and AA meetings are the two things helping him maintain his sobriety. He seemed very cool and collected and interested in how the other comics were doing. I’d talked to Williams offstage once about five years ago, and it reminded me that this is an even more interesting guy to talk to when he’s not trying to be "on."

At the late late show, Chappelle took audience requests and laughed early and often at his own jokes for about 55 minutes. He said a woman suggested he read “The Secret” to help get over the $50 million deal he walked away from with Comedy Central. “Positive imagery? That’s the secret? Go to Africa and tell some starving kids that (expletive)!” He also can sing quite a bit of John Mellencamp’s 1982 hit, “Jack and Diane.” He told the audience: “Put that under song lyrics I didn’t know how the (expletive) I knew them for $1,000.”

Chappelle was turning heads on MacDougal Street all weekend, hanging outside the Cellar and Olive Tree Cafe with other comedians Friday, Saturday and Sunday. He declined most but not all photo requests from passersby, saying he didn’t want to set a precedent that’d have him taking photos all night long. Fair enough. Very easygoing guy, considering all of the hassles he puts up with — then again, he does spend a lot of time on his farm in Ohio. Which probably also explains why he comes back to NYC every once in a while to feed his need for laughs at the Cellar. He said he also likes to work out at the Punchline. At one point Sunday night, he turned to me and said, “My life is weird, man.” Didn’t need to tell us that, Dave!

Related: An edited version of my account appears in today’s Rush and Molloy column.