My husband is wise. He has given me a few little sayings that I don't think I'll ever forget. Here are two big ones that come to my mind.
One is "No guy wants to be just friends." Basically, he was telling me that no matter what the friendly gentleman is saying, he wants to date the girl, not be "just friends." I have never found that to be untrue.
Another is not an exact quote, but two similar ideas: "Be careful of the running of the mouth." "When you are telling someone a secret you have to think 'Who does this person like better than me?'"