‘Tell me, Stephen, what did you drink on that infernal rock?’

‘Boiled shit.’ Stephen was chaste in his speech, rarely an oath, never an obscene word, never any bawdy: his reply astonished Jack, who looked quickly at the tablecloth. Perhaps it was a learned term he had misunderstood. ‘Boiled shit,’ he said again. Jack smiled in a worldly fashion, but he felt the blush rising. ‘Yes. There was one single pool of rainwater left in a hollow. The birds defecated in it, copiously. Not with set intent – the whole rock is normally deep in their droppings – but enough to foul it to the pitch of nausea. The next day was hotter, if possible, and with the reverberation the liquid rose to an extraordinary temperature. I drank it, however, until it ceased to be liquid at all; then I turned to blood. Poor unsuspecting boobies’ blood, tempered with a little sea-water and the expressed juice of kelp.’

HMS Surprise – Patrick O’Brian