“Have you ever seen a saxophone opening a stand up comedy set? I don’t think so. Anything can happen on Stand Up on the Spot!”

Jeremiah Watkins, the host of Jeff Ross Presents Stand-Up On the Spot, made his entrance Tuesday night playing the sax while his sidekick, Avery Pearson, tickled the organic ivories onstage at Katacombes for the first of three nights at Just For Laughs Montreal.

It’s one of three improvised stand-up showcases at JFL this July — four, if you count Jeff Ross & Dave Attell: Bumping Mics, which finds the two headlining vets riffing together onstage after midnight. The others are Set List (which finds comedians following a surprise set list presented on the screen behind them), and What’s Your F@#king Deal?, in which host Big Jay Oakerson and comedians have to rely solely on crowd work and not their prepared acts.

For Stand-Up On the Spot, the audience gets to be in charge, hollering out suggestions to start off routines as if the stand-ups were solo improvisers. Which they become for 15 minutes or so, at least, in this show. “More suggestions than heckles,” Watkins tells the crowd. “‘Big nose’ would not be a good suggestion, for example!”

Last night at @justforlaughs, #standuponthespot improvised stand-up sets

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Stand-Up On the Spot also finally allows Watkins to take center stage — you’ve likely seen him before on Comedy Central running around on the periphery, as part of “The Wave” on Roast Battle or as part of the crew on The Comedy Jam. Here he gets to show off more of his comedy muscles, as well as his musical ones.

As for the comedians on Tuesday night, Bryan Callen showed off his UFC and shark-punching skills. Or lack thereof.

Tony Hinchcliffe hated most of his suggestions, and used his roasting skills to full advantage.

Katherine Ryan, a native Canadian who’s made a name for herself on British TV panel shows, confused an initial shout of “shiny slippers” with “Chinese slippers,” and quipped: “And now we know who the racists are.”

Special guest Jimmy Carr loved this show’s premise, of course. He famously invites audience members to attempt to take him down during his headlining act, only to to outwit them at every turn. After receiving requests for the deadly serious topics of Putin, Trump and North Korea, Carr regaled us with even more serious facts about them all. “Just an indicator of the circles I move in,” he added. “I’m better than this venue.”

Australian Wil Anderson immediately launched into a filibuster of a rant, and when he finally let up for a moment, a guy in the front row asked what stand-ups say to each other. Anderson laughed it off by referencing having to follow Carr! “I don’t know if I’ve taken a suggestion but I certainly haven’t taken a breath,” Anderson joked.

Mike Birbiglia, another unannounced guest, opened by forewarning that this whole idea “is a horrible mistake,” adding: “I just think comedians without jokes are sheer depression.” Nevertheless, Birbiglia made light of his marriage and may have found a new bit in there, to boot.

Ross closed out the night’s showcase, and in his ad-libs discovered ideas for a potential tattoo, as well as a backup career in case this comedy thing doesn’t work out. “New material might,” Ross said. “This is so much fun Jeremiah.”

Indeed it is.

Jeff Ross Presents Stand-Up On the Spot with Jeremiah Watkins, playing tonight at Katacombes, and Thursday at the Montreal Improv, during JFL Montreal.