You can find big-character style propaganda all over China. In Beijing, you can always find the random billboard proclaiming the generic "Long live the People's Republic of China," the Taiwanese related "Support the 'One country, two systems' policy," or the self-contradictory "Vigorously uphold Mao Zedong and Deng Xiaoping thought" (self contradictory because Deng, when not busy running over unarmed student demonstrators with tanks in Tiananmen square, did a lot to introduce free market reforms to the communes created by Mao.)
However, it's in rural China where you see the slightly stranger signs. Some of the ones I saw said:
"Every married woman with children must have a "woman's" exam four times a year."
"Less births, excellent births. For the Country, for the people."
"One person does drugs, the entire family collapses, society is damaged."
"No Communist party, no new China."
"Happiness is one birth."
"Fewer births will lead to quicker riches."