China Propaganda banknotes during WW2 - Central Reserve Bank Of China 10 Yuan Banknote (1940)

This banknote depicts 10 turtles hidden in the border. The turtle is held in low regard by the Chinese and Japanese because it lays eggs and then leaves them. The children are like fatherless bastards. A subtle insult by the Chinese.

Smith and Matraver add:

The turtle, of course, is an animal held in low regard by both the Chinese and the Japanese. Its appearance on these notes undoubtedly amused the substantial majority of Chinese who opposed the Nanking government, but if the Japanese military authorities were not amused, they did nothing to halt the continued issue for an extended period.

Bruce W. Smith adds:

In regard to the meaning of the turtles I was told by one Chinese specialist that "turtle’s egg" is a swear word in North China. It is equivalent to "Bloody bastard."

Harry W. Atkinson says:

"Egg of a turtle" is an insult. I would warn anyone against calling the chef in his favorite Chinese restaurant, "Wang Ba Doon," especially if the chef has a knife in his hand. "Egg of a turtle" is such a crude and insulting remark to a Chinese steeped in ancestor lore that decent Chinese hesitate to even say or write the characters fore this term.