It’s Monday night, it’s Birmingham and Frank Skinner is talking dirty to 5,000 fans. And if the vivid details of Skinner’s scattershot sex life don’t grab you, maybe you didn’t read the poster right.

“Warning,” it says, “this show is not for the fainthearted.” Faintheart or not, I love a lot of Skinner’s new show, a prototype of which he played in Edinburgh in August. Back then, Skinner wasn’t quite match-fit, after ten years away from live comedy, concentrating on his chat shows and Fantasy Football League. Three months of touring later, a tentative joke-jabber has become a stand-up prize fighter. Slight, moisturised and big-browed, he looks like a cross between a choirboy and Ken Dodd. But he prowls the NIA stage with as much spunk as any of the rock gods that play here, his new gold tooth glinting out from the three megascreens high above the stage.

What your average rock god won’t do, and what Skinner excels at doing, is debase himself. He tells jokes about paedophiles, Parkinson’s disease, potentially predatory gays, David Baddiel’s self-pleasuring techniques. But however laddish or gnarly some of his material, it’s mostly made harmless by the way he implicates himself. He’s just turned 50, and he’s feeling it. He’s having nasty falls and forgetting things. Now that he’s taking an over-50s multivitamin, his urine glows in the dark – “You should see my toilet, it’s like flying over Vegas”.

Skinner marshals his material brilliantly, interacting with the crowd or launching into set pieces as if it were all part of the same spontaneous thought process. He’s one of the few comics who can play a room this big because, like Billy Connolly or Victoria Wood, his language is so evocative: “like a lizard’s inner thigh,” he says of his laugh lines. One man and a mike becomes a vivid visual experience.

But he’s a bit too vivid sometimes. “I used to put myself about quite a bit, sexually,” he says, before leading into an overlong exegesis of his shagging antics. When he’s still mocking himself, it’s funny: he wanted the woman to go home as soon as he’d “completed the act”, he tells us, although maybe the women felt the same. “I don’t know. I’m normally on the bus by then.” But he gets lost in the nitty-gritty. There are more intimate details than the jokes can sustain; after five minutes, you’ve got the idea. After ten, the vision of Frank’s bony bottom at work has burnt its way into your brain. Really, I could do without it, Frank.

The less blue material is told with the energy and sure sense of structure of a great comic. It’s a good show. But if he would interruptus his tales of coitus a bit sooner, it could be a great one. On tour.

— Next show Wednesday 21st November, Birmingham NIA. www.frankskinnerlive.com

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