To be open and aboveboard.

　　As clear as crystal.

　　eg：A gentleman' s activities are open and aboveboard.

　　中英俚语俗语来源：晋书："大丈夫行为，当磊磊落落，如日月胶然。"

　　同义词：胸怀坦荡 As open as the day.

　　反义词：鬼鬼祟祟 Up to some hangky-pangky.