Seinfeld surprise stand-up

WHEN Jerry Seinfeld hits a comedy club for a surprise performance, the fans swoon, but other comics are left to sweat over their sets!

Spies told us Seinfeld spontaneously showed up this past week at the West Side Comedy Club on 75th Street to try out some new material between tour dates at larger venues.

Seinfeld had tweeted to his 4.2 million followers that he was going to drop into the club at “8:30-ish.”

Recounted comic Jeffrey Gurian, who was scheduled to perform that night: “Suddenly, just before the show started, a lot of people started showing up. Then the manager came and told us that Jerry Seinfeld said he was going to stop by.”

When the comic legend arrived with his “baseball cap down over his eyes,” the club’s manager asked Seinfeld if he wanted to get onstage right away.

That’s when the first comedian scheduled for the night took off. But Seinfeld decided he needed a beat.

“Most comedians like to wait a few minutes before going right up onstage, so the manager looked at me and said, ‘Jeffrey, you’re up!’ ” said gobsmacked Gurian. “And before I even had a chance to think about it or get nervous, I got to perform in front of Jerry Seinfeld.” Jeff mused, “Not sure why, but I felt calm.”

But Gurian switched up his set. “Very often I start out telling jokes about the weather, cellphones and texting,” he said. “But for some reason, this night I decided not to, and when Jerry went up right after me, among other things, he did jokes about the weather, cellphones and texting. I thought to myself, ‘Well, at least I have good taste in choosing topics for material.’ ”

Seinfeld followed with a “killer” set of new jokes, then a Q&A. A fan told us, “Jerry said the only two things he likes to do are ‘Comedians in Cars Getting Coffee’ and doing stand-up . . . Especially at this club, because it’s in his neighborhood. Then he left alone with his hat pulled down over his eyes again.” Seinfeld next played Caesars Palace in Las Vegas.