Kiss and Tell

"Disclosing private or confidential information, especially in a first-hand account: a kiss-and-tell memoir by a Presidential aide. Betray a confidence, as in A real lady doesn't kiss and tell. This idiom originally alluded to betraying an amorous or sexual intimacy. First recorded in 1695, it is still so used, as well as more loosely, as in Don't ask how I voted; I don't kiss and tell." Definition by awnser.com