I Can't Read It Anyway!:
As if the Chinese language isn't difficult enough for us alphabetical Westerners, what's with the upside-down character one sees on so many doors and windows during, and left up after, Chinese New Year?
The character is 福, fu, pronounced “foo”. It means fortune or luck.
A Play on Words:
In Chinese, saying Fu dao le means "luck or fortune has arrived". But the word "dao" can also imply to fall down or turn upside-down. So, literally turning the character 福, fu, upside-down is a play on words implying fortune has arrived.
Paint the Door Red:
You'll see the character, usually written in gold on a red background, hung on doors across the country by Chinese hoping for good fortune for the new year. The decorations are often left up all year so you may see it at any time. And why not? Everyone needs a little fortune heading their way.
And now you know why that character is turned upside-down on doorways across the country. Now, let's see about the other 20,000 or so Chinese characters you'll need to become fluent...