December is a month when a Japanese party or Bōnenkai (literally “forget the year gathering” in Japanese) are held among

co-workers or friends and sometimes sponsored by a company for their employees. Bōnenkai are held, as the name implies,

in order to wash off the unpleasant memories of the passing year and prepare to welcome the new year with fresh mind.

The tradition started in the 15th century as gatherings to express thanks.

Currently, Bōnenkai are seen as times for letting one’s hair down and having fun without worrying about the boss/employee

formal relationship or the rank and age differences, because the relationship in the workplace in Japan is often fairly strict,

as exemplified in humble and honorific forms in Japanese.  Office workers are expected to use these words properly according

to the situation in a workplace.  In addition, they usually have to put more emphasis on harmony with others rather than

having their own thoughts to have a good relationship at their offices.

You’ll often hear people saying “Let’s do away with all formalities and have a good time tonight”.

You should be wise enough not to take such a suggestion literally.

http://www.nicjapanese.com