I'm still not quite sure what it is about the semantic gymnastics of puns that's so satisfying, but we seem to be ingrained with a reflex action to snort with approval whenever we hear homophonic wordplay. Darren Walsh exploits that to good effect in Punderbolt, cruelly manipulating as he does the fact that as a species we laugh involuntarily when we hear words being misused for their phonetic properties.
There's plenty of pun-merchants in mainstream comedy, with the Vines and the Miltons of this world battling for idiomatic supremacy, all the while trying to find an original way of delivering endless one-liners over the course of an hour. Walsh's gambit is to keep things fresh by alternating between mediums, combining projector-based humour and physical props (such as instructing an audience member to hold a sign with the word "grudge" written on it and letting everyone uncover the joke for themselves). The shifting format succeeds in sustaining interest, which can be a tricky task when you're essentially attempting to make people laugh every four seconds.
For every few throwaway cringe gags there's a brilliantly dense image, a mixture of logic and phonetics that lingers in the mind. Usually, though, by the time our subconscious has deconstructed it he's reeling away in search of another knee-jerk chuckle. There's a fine line between groans and laughs with quickfire wordplay, but in general his quips are pithy, concise constructions, featuring enough rapidly delivered portmanteaus, non-sequiturs and homographs to last you a good while.