At a reception McKay attended, the hostess served rum cake.

”All the guests hesitated, watching to see what McKay would do. He smacked his lips and began to eat.” When one guest expostulated, “‘But President McKay, don’t you know that is rum cake?’ McKay smiled and reminded the guest that the Word of Wisdom forbade drinking alcohol, not eating it.” (David O McKay and the Rise of Modern Mormonism, p 23)