You can get away with pretty much anything in comedy - hell, in life, too - if you only commit to it enough. That sort of commitment can surface in excitingly angry Edinburgh Fringe stand-ups such as Brendon Burns or Jerry Sadowitz. But it's also what makes the difference between a compellingly odd comic vision and resistible whimsy.

Take Kristen Schaal and Kurt Braunohler, New York comedians plying the sort of wilfully daft double act that just looks like graduate jollies when so many British comedians try it. They mount a silly drama, Double Down Hearts: “A play,” promises the blond, pseudo-earnest Braunohler, “that would bring Chekhov to his knees.” They show Pocahontas and John Smith having phone sex.

Schaal, who plays the kooky fan in Flight of the Conchords, is an outstandingly assured yet vulnerable stage presence as they spat, sometimes with surprising venom. They get away with their nonsense by investing it with just enough realism to make it grip for as long as it lasts. Which isn't long enough - they're gone after 50 minutes, in sore need of a better finale. But there are sparks of something glorious in here, not least in their video adventure spoof Penelope Princess of Pets, at least one episode of which you can find on the internet.