Stand-ups use familiar old material at their peril. Lifting routines from other comedians? Also frowned upon. By those standards Rainer Hersch's Victor Borge should be run out of town, his long tuxedo tails flapping behind him.
Because this performer, who is half-English half-German - "Any German people here? Comedy show. Hardly likely" - does both.
But his homage to Victor Borge isn't just a cover version of the late great Dane and those ivory- and rib-tickling routines which took him from Copenhagen to Broadway to television-powered international fame through the 50s, 60s and 70s.
No, it's part one-man theatre piece, part live biography, part stand-up, part sit-down piano bash and totally terrific.
Yes, it does help if you've heard of Borge, who in his heyday was to comedy what Scandinavian near-neighbours Abba were to pop. This is being written by someone who interviewed Borge on his final New Zealand tour and barely got a question out due to being rendered a starstruck seven year-old by his memories of his tv shows decades before. But it's not an absolute requirement and looking back now through Hersch's eyes, it could be said Borge, was a man ahead of his time. His phonetic punctuation? Text language in its infancy, surely. Grafting Happy Birthday and Chopsticks into Moonlight Sonata ? Borge was clearly the first master of the mash-up.