家常便饭 jiā cháng biàn fàn

家常便饭 jiā cháng biàn fàn

解释：1. 家里日常普通的饭菜。2. 经常发生的事情。

Explanation:
Literally it means very comman meal, nothing special or unusual. It is usually used to mean things happening quite often.

Dialogue:
A：zhème wǎn hái jiābān?
A：这么 晚 还 加班？Are you working overtime so late?
B：jiā cháng biàn fàn le.
B：家 常 便 饭了。Oh, it is common.