Daniel of Beccles wrote in his book Of the Civilized Man (Urbanus Magnus), a three thousand line work on the subject of manners sometime in the 13th century, which included some wonderful words of advice on dining etiquette. I am particularly taken with his last suggestion:
Should you desire to fart, remember first to gaze up at the ceiling.
If you need to clear your nose, do not show others what appears in your hand.
Do not omit to thank your host.
Abstain from mounting your horse in the hall.
It is unseemly to fall upon your host while he is voiding his bowels.
Finally, if while dining in the company of your liege and his wife expresses her desire for carnal knowledge, the best thing to do is to pretend to be ill.