From Chin Kee Onn’s famous Malaya Upside Down, about the Japanese occupation of Malaya during WWII:

Hatred of the ‘communists’ became a Japanese obsession, and so great was it that anyone who had the slightest pro-Allied sentiment, anyone who made the slightest criticism against the Axis powers, anyone who listened to a short-wave radio, anyone who spread war-news, anyone who spoke ill of the Administration of any of its officers, anyone who ridiculed new served up by the newspapers, anyone who complained of the shortage of the necessities of life, anyone who complained of the high cost of living, anyone who made too many enquiries, anyone who talked about the worthlessness of military scrip, anyone who made a joke about Nippon-go, anyone who belittled the virtues of the Savings Campaigns, anyone who passed sarcastic remarks about the Heihos (volunteer auxiliary service corps), anyone who spoke against Nippon music, anyone who laughed at the I.N.A. (the Indian National Army), anyone who did not respect Nippon-zin, must be a communist!

What was the joke about Nippon-go?

Walls and advertisement boards would bear the caption ‘Nippon-go—America come’!

In other words, a joke about the military administration’s efforts to spread the Japanese language [= nippon-go] in Malaya. How interesting that the “communists” (real or imagined) hoped for the Americans.