A expressão “do caralho” devia constar nos dicionários. E a explicação seria essa aqui:
World Barista Champion Gwilym Davies has devised an interesting concept – the disloyalty card.
Davies created the card to encourage his clients to sample the wares of quality coffee shops around London. If a disloyalty member tries all 8, he will make you a free drink at his shop, Prufrock Coffee.