“Some teach that a boy should keep in the gas of his belly by compressing his buttocks. But it is not civil to become ill while you are trying to seem polite. If it is possible to leave, let him do it alone, but if not, follow the ancient proverb: Hide the fart with a cough.”
Desiderius Erasmus, De civilitate morum puerilium
Erasmus, Prince of Humanists: author of groundbreaking scholarship and incisive social criticism. Oh, and master of the ancient art of fart concealment.
How to Sit at the Table, 1530, here.