Best Boy is one of those job titles you see in the closing credits of movies, prompting the question, "what does one of them do?" On this evidence, the answer must surely be that they write and perform sketch comedy: elaborate, anarchic, surprisingly dark and very funny sketch comedy.

The two performers who make up Best Boy, Charlie Mizon and Dan Smith, quickly establish themselves in a classic pairing. Mizon is the effusive, creative genius behind the act; Smith is something of a good-looking simpleton. Their attempt to play their sketch show straight runs purposefully awry, as Mizon injects new approaches to shake things up, and Smith grows increasingly frustrated that his (inane) contributions aren’t getting the recognition he feels they deserve.

The best gag comes through one of Mizon’s excursions – this time into magic – as a trivial and hammed-up card trick sets up a running series of punchlines. It culminates in a reveal that underscores their commitment to the joke, in a rather permanent way. I also liked the ongoing skewering of commercial influences at the Fringe through the medium of “sponsored” sketches – and I can advise that you sit near the front if you’re a fan of a certain brand of spiced, cured, condom-wrapped meat sticks.

There’s a good deal of audience participation, though the pair were able to take advantage of a sizeable crowd to spread out their attentions. A mass sing-along felt like a lot of effort for a slightly weak joke, but the gloriously silly looped ending worked well, with each iteration adding another level of complexity and hilarity to the farce. Crucially, even when picking on audience members, it never became too much; everything is done in good humour, with Best Boy themselves as the mark.

This was particularly true of a sequence based on scripted heckles, which started to reveal the refreshingly bleak side to their comedy. The washed-up club singer and the stickler for grammar are also very much in this space, and were well-played. But at other times, I sensed they were just on the cusp of being needlessly cruel (as in a dark fairytale about premature birth). It’s dangerous territory – but they always pulled it back with a wink and a nod, and an appreciation of how far to push the joke.

As daring at times as it is charming throughout, Best Boy is a gripping comic routine from two electrifying performers. Even if obscure puns about movie production roles don’t impress you, this expertly-devised and delivered sketch show surely will.