Wartime survivors (customers who lived) always followed the Geneva Convention (acted very polite to each other), because anytime one of them violated it (was rude), they were summarily executed (shot at the instant they were rude), and shipped off in a body bag, assuming that much of the casualty of war (deceased ex-customer) was left; combatants didn't always have rations (bag lunches), so they often engaged in foraging for food ("Donner Parties,") a practice better left undescribed.

Dear Sirs: As a Naval officer, I abhor the implication that the Royal Navy is a haven for cannibalism! It is now known that we have the problem relatively under control, and it is the RAF who now suffer the largest number of casualties in this area. What do you think the Argylles ate in Aden? Arabs?! Yours, etc. Captain B.J. Smethwick, in a white wine sauce, with shallots, mushrooms and garlic.
Monty Python's Flying Circus, Royal Episode 13
I liked Harris. He might have been better done, perhaps, but I am free to say that no man ever agreed with me better than Harris, or afforded me so large a degree of satisfaction.
Mark Twain, "Cannibalism In The Cars"
Hunger unwound what little hope was left and moved us to what humanity would not once have contemplated.
Comdeus Canto, survivor of the expedition from the Inferno’s Child, Warhammer 40,000: Rogue Trader
In the frozen land of Nador, they were forced to eat Robin's minstrels. And There Was Much Rejoicing (Yay).
—Monty Python and the Holy Grail