Greg Davies, Bloomsbury Theatre

Greg Davies is a comedian who laughs along to his own material. A conspiratorial look glints in his eye, a hint of fruity mischief plays on his lips. The adage that you should never be amused by your own punchlines is, of course, a tall tower of rubbish – different jokes for different blokes – but Davies’s enjoyment of his own routine begs a couple of questions. Is it as funny as he thinks it is? Or is it funny because he thinks it is?

And then there is the greatest existential quandary of all, which has knitted the brows of philosophers since time immemorial. Exactly how hilarious is fellatio?

Davies, who forms one third of We Are Klang, is touring on his tod for the first time. There’s more than enough of him to go round, of course, being of slam-dunking loftiness (six foot eight, he establishes right at the start). And in his middle years his width is catching up with his height. The spilling gut, quite apart from popping the buttons on his shirt, gives him the odd posture of a wading bird attempting to stand scrupulously erect.

The show he’s touring goes by a nonsensical and wholly misleading title. There isn’t an hour’s material in Firing Cheeseballs at a Dog. Davies uses the eponymous moment in which, bizarrely, he experienced an epiphany of pure happiness as a springboard to discuss the ways in which his life has, for the most part, fallen short in that area. This is of course standard stand-up fodder – the perennial issue of not getting enough sex, not being good at it when you do get it, having embarrassing parents. No comedian (with one famous exception) makes a meal of his successes. But Davies dips into his own failures with a nice mix of charm and genuine mystification.

The autobiographical narrative is structured around phases, the two key ones involving school, first as a pupil and then as a teacher. In both Davies profitably homes in on the random cruelty and sheer oddity of children. Analysing their gift for nicknaming, he invited participation. That this audience’s examples - including Tripod, ET (Elephant Tits) and John Lennon (for a female) - produced some of the bigger laughs of the night would have threatened most comedians. But Davies exudes a generosity of spirit that is inclusive and unadversarial. No humiliating the front row for him – when anyone nipped off to the loo or the bar he batted not an eyelid.

As he moved onto middle age he found one person in the audience who was only 15. “Too young for this!” he sweated, but that’s clearly not the case. Davies certainly has an oral fixation. The jokes about blowjobbery in all its forms, from pubertal auto-fellating to one’s elderly mother unknowingly miming the act, were rolled out throughout, but Davies’s enjoyment of seminal fluids and faecal material is delivered in the spirit of a schoolboy. His is essentially an innocent, humane and, when he finally discusses family illness, even compassionate worldview which celebrates dysfunction and eccentricity instead of deriding them. Hence all that hilarity up there onstage. For this tall teller of short stories, the laughter is all with rather than at.

• Greg Davies is on tour until 10 December

Watch Greg Davies on the troubles of being tall on Mock the Week: