Most comedy shows, like most reviews, come with some kind of inbuilt narrative, some trajectory from A to B that allows the performer to hook on their best jokes, anecdotes and observations like some kind of hilarious washing line. Gary Delaney's Purist sods the washing line, choosing instead to deliver what might be described as a dirty laundry basket, full of assorted one-liners and quips and when I say dirty, believe me, I mean it. Delaney's material is completely unacceptable. It also happens to be absolutely hilarious.As might be expected from a theme-less stand-up set, the topics themselves are a mixed bag, ranging from wordplay about 90s Britpop to the funny side of child abuse. It's astonishing what Delaney's skill in both writing and delivery allow him to get away with. Most of the time he seems astonished too, throwing poker chips into a bucket labelled 'Comedy Hell' and testing the audience to their dark, shameful limits. Tellingly there's a charity collection on the way out, offered as a karmic sop to those he will inevitably have offended.Make no mistake: this is criminal wit, but Delaney is a masterful evader of justice. Frequently it's so near the knuckle that it's on the knuckle, and the knuckle is part of a fist which is punching you squarely in the sense of decency and social decorum, but if you've got a strong enough stomach you'll be laughing too hard to feel the bruise.Evidently this sort of thing could get wearing if the hit rate were not so surprisingly high. It's true that you can sometimes prempt which way the puns and quibbles are going, but that frequently awful realisation makes the pay-off all the funnier. The constant, undirected stream is slightly broken up by some impressively tight set-pieces, with an A-Z of one-liners a pretty astounding feat. His slideshow of edited Wikipedia entries isn't bad either.The nature of the show means it's highly quotable, but I'll resist the urge to give anything away not that there's any kind of narrative to ruin, but each joke is such a surprising, disgusting delight that I'd be better off leaving it to the expert. Not pure at all, but very, very funny.