Help me with my boss! How can I bring to light his nepotism and unethical behavior to the people that matter?

I don't want to leave my job b/c everything else about it is great. He lies to the bd. of directors constantly. He works maybe 25 hrs/week yet tells them 40+. My morale and motivation has steadily declined to the point where I will definitely get fired for not holding my tongue after listening to another one of his lies or stupid stories.