Will you make it through the door of the Royal Academy, where two young people currently face each other, naked, like a pair of human gateposts? Not if you are too tactful (or too portly), afraid of grazing their bare bodies with a sharp buckle or zip. But there is a secret bypass into the next gallery that allows you to watch footage of the original and more startling performance of this artwork, in any case, and avoid the keyed-up RA queues.