光明磊落
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.