Today is a traditional festival in China -- The Double Ninth Festival. We Chinese celebrate it on the ninth day of the ninth month in Chinese Calendar.
In the traditional theory of YinYang, 9 means the extreme Yang. So you can see how Yangs double 9 brings. One of empire of Han dynasty named this double 9 date to be a festival. In this date, people were customary to climb the high mountain, drink chrysanthemum wine and eat double ninth cakes which are made by sticky rice(also called chrysanthemum cakes or flower cakes).
With the days past, people endow a new meaning to this festival, to respect elder people, to wish elder people to live to 99 or older.
Nowadays, these activities become obsolete for people in modern cities. They are too busy to climb the high mountain and nowhere to buy chrysanthemum wine. The only convention is to eat double ninth cakes. I did this morning. This reminds me what date is today.
Reference: Double Ninth Festival in Wikipedia