Takeshima Day

I hardly know what to make of this, so better that you educate yourselves.
Ask your favorite search engine to return webpages containing the words "Takeshima," "Shimane," "Japan," and "Korea."
Then run the same search again, only replace "Takeshima" with "Tok-do."

And since most of the results for either search will be for Japanese news outlets, make sure you hit a Korean site, too. They'll tell you why exactly South Korea is so pissed about this. The Japanese news is notorious for reporting that the Koreans are pissed, but rarely give any explanation.

Takeshima means "Bamboo Island."