Edinburgh is as much about the night-life as the day-life, and it's not just for barflys; most comedians and comedy groups up at the fringe promote their shows by taking part in cabarets and night-time revues. It's a way to perform in front of new audiences and advertise a show, especially for young up-and-coming acts.
Dec Munro is the compère for revue shows Test Tube Comedy  and Edinburgh Must-Sees. “At Test Tube we've had some acts that have done very well,” he says. “[Comedian] Tony Law did a set there that went down brilliantly, and literally half the crowd went to see his show after that. That also happened with Nick Sun, and with a beautiful theatre piece called Slow Clap. There is an element of promotion – but obviously it depends how well your material goes down.”
Spank, in a sweat-box of a basement cave at Underbelly, has gained a reputation for being the most raucous of all the late-night revues. There is a moment at the end when performers can make their pitch to the audience – as long as they are naked on the stage.
These late-night revues can be brutal for performers. In front of a drunken audience, it's possible to really strike a chord- if you bomb, you really bomb. “The audiences at some of the late-night places can be... testing,” says Munro. Because they're all wasted? “Yeah.”
Mark Cooper Jones is one quarter of sketch comedy act Wit Tank , regulars at Spank  and other places; tonight, they are due to play another, Live at the Electric . “The experience is brilliant. Its lots of fun. It depends on the kind of act you are; we're quite a loud, shouty group. You have to shout over the top of the audience sometimes, but it's a laugh”
“It can get bad,” he continues. “I've seen people tank before, if they can't get on top of the crowd. You've got a bear pit in front of you, and if you have a weak beginning... it can be horrible.”
“Do you know the Scott Capurro story?” Munro asks. This tale has entered Edinburgh festival lore. Comedian Scott Capurro, having bombed on stage at the Gilded Balloon's Late and Live , was forced by a baying crowd to urinate on his own jumper and shoes, live on stage. In a surreal twist, Jimmy Carr, who was performing after him, had to mop it up before he could perform his act. “Arguably,” says Munro, “that's not the best way to promote your show...”