For curious monolingual folks like myself, the labels on those bags (haricots de Soissons) indicate that they’re full of beans. You can see a similarly NSFW example of a postcard referencing General Oku Yasukata here along with the following explanation:
…In French, “au cul” means “at/on the ass.” Thus, as Linhart explains, “Oku” and “ass” are homophones in French, restricting the pun to a play on the French figure of “General Ass.”
For curious monolingual folks like myself, the labels on those bags (haricots de Soissons) indicate that they’re full of beans. You can see a similarly NSFW example of a postcard referencing General Oku Yasukata here along with the following explanation: