Around half an hour into Lee Mack's routine at Sheffield City Hall, he asks one of the technicians to put a spotlight on audience members to his far right.
In a coincidence, Sheffield suffers a power cut that leaves the next 10 to 20 minutes of Mack's routine bizarre to say the least.
It's obvious he's encountered many things over his 20 year career in comedy, from hecklers to rowdy members of the audience, but a blackout was a rarity.
Eventually, power returns to the City Hall, and Mack regains his footing.
Some comedians take their time telling gags, while others are like race car drivers, putting their foot down on the comedy gas pedal and rarely letting up for the duration.
Lee falls into the latter camp, so when he hits that technical speed bump, it's amazing how well he recovers.
(I am a little biased. I've interviewed him a couple of times; think his sitcom Not Going Out is a finely tuned cracker, and his autobiography, Mack the Life, is a great read.)
Pacing the stage like a caged animal, it wasn't hard to see why he's among the best comedians working in the UK today.
Mack does a great job of creating comedy waves, and then surfing the crest.
It helps that his support act was Mike Gunn, one of the best warm-up guys I've seen, though an audience member did generate a superb, unexpected. punchline.
"Do you know what Saga stands for?" asks the comic.
"Send a granny abroad," replied the audience member.
It brought the house down.
It's unlikely you've seen Gunn on the usual panel game circuit, whether it's Mock the Week or 8 out of 10 Cats, but given the quality of his material and his delivery, he deserves mainstream exposure.
The strange thing is, when the audience spilled out onto Sheffield's city streets, it was hard to recall a single punchline from the evening, but even with the technical glitch, it was well worth the 86 mile round trip.
It helps that Gunn and Mack had created such a wave of goodwill, because getting out of Sheffield during a power blackout, with a confused sat nav and traffic lights stuck on red, was no laughing matter.
You may wait for the pending the DVD of Mack's live gigs, but in this case it's well worth 'going out' and catching the duo in action.