The Chinese characters 到 (arrive) and 倒 (upside-down) are both pronounced "dao". During the Chinese New Year festive period, the character 福 ("fu", literally meaning auspiciousness, blessing or happiness) is displayed inverted, so that fu dao ("reversed fu") also suggests luck or fortune has arrived.
Legend has it that Zhu Yuanzhang (朱元璋), the first emperor of the Ming Dynasty (1368-1644), once planned to kill a family that had insulted his wife, Empress Ma (马皇后), and marked them with the character 福. In order to avoid bloodshed, the kind hearted Empress Ma ordered every family in the capital to paste the character 福 in front of their doors.
Everyone followed the empress' instruction, but one illiterate family had pasted the character upside down. When the emperor's soldiers went through the streets, they found the character pasted everywhere, including the one displayed upside down. The emperor was very angry to hear their report, and ordered his his soldiers to kill the family who had pasted the character in the wrong way.
Empress Ma saved the day with her quick-wit, "That family had known that you would be coming to visit them, so they pasted the character upside down intentionally. Doesn't that sound like "fu arrives" ? Upon hearing this, the emperor was appeased and a tragedy was averted.
