đóng cửa bảo nhau 
it’s better not to wash one’s dirty [ đóng ] : to close, shut, build, drive (nail), play, act (in a play)
[ cửa ] : door, window, entrance, opening
[ bảo ] : (1) to say, order, tell (someone to do something); (2) to insure; (3) to protect, guard; (4) precious, valuable
[ nhau ] : (1) together, in company, each other; (2) placenta
Most Common Compounds Set 1:
Most Common Compounds Set 2 :