Rumpy pumpy - or, at least - pumping a rump has never seemed so painful, in a play that starts with a bang and speedily descends into a protracted, tedious whimper. The scenario sounds ripe with bawdy potential - boy meets woman, boy gets woman, they have anal sex, he gets stuck and calls on his gynaecologist father to help separate them - but in fact it just feels like a nasty case of anus horribilis.