The writing says (I'm told) "Merry Christmas" in Korean. The Institute for Religion and Democracy (an "ecumenical alliance of U.S. Christians," principally Methodist, Presbyterian, and Episcopalian) is distributing them (at one dollar each) as a way to raise awareness of the plight of Christians in North Korea:
Christians continue to be a particular target of the Kim Jong Il regime. When they are discovered, they are executed or sent to prison camp, along with up to four generations of their families. In the prison camps, Christians are constantly pressured to renounce their faith even as they are literally worked to death. Forced to do particularly dangerous work, they are subject to frequent torture and abuse. They are starved to death, as well.
The IRD suggests wearing these buttons is a good way to counter the "the holiday that dare not speak its name" trend in the United States. That may be, but of course their major point isn't about social pressure in America; it's about the execution and imprisonment of Christians in North Korea.
When we read about the various fatheads around the country who won't let Nativity scenes be set up on public property, before we cry, "Help! Help! I'm being oppressed!," perhaps we should say a brief prayer for the North Koreans who are being killed for their Christianity practiced in secret.