What does 다반사 (茶飯事) literally mean?

 ANSWER: a tea (茶) and rice (飯) matter (事)

Koreans drink tea, Koreans eat rice;

한국인은 차(茶) 마시고, 밥(飯) 먹는다.

For them, it's a common, daily routine.

그들에게는 일상대반사(日常茶飯事)이다. 

The Chinese character for "tea" is 茶 (다), and the character for "boiled rice" is 飯 (반), so since 事 (사) can translate as "work," "occurrence" or "matter," the phrase 다반사 (茶飯事) can literally translate as "a tea (茶) and rice (飯) matter (事)." And since 일상 (日常) can translate as "daily," 일상다반사 (日常茶飯事) can translate as "a daily event" or "an everyday occurrence (affair)."

From Dong-A's Prime Korean-English Dictionary