Shigotoosame(仕事納め）means last business day of the year.
In Japan, December 28 or 29 is usually the last day of work.
Here are some example sentences using the phrase "仕事納め Shigotoosame".
[今日は仕事納め！頑張るぞ〜 :)] Today is the last day of work! Let's work hard!
