One's true or honest beliefs, thoughts, convictions, biases, desires, etc.; one's real personality, character, or disposition. (A less common variant of "one's (true) colors.") Dave said all along that he only wanted this deal because it was in the company's best interest, but he showed his true stripes once he realized that he wouldn't get any special commission for his efforts. You will really see your friends' true stripes when you call upon them in a time of crisis.