This phrase was coined by Bill Milliken when he published the book of the same name in 1968 and revised it with Char Meredith in 1971.
It has become widely used and copied with numerous authors writing books of the same title or employing the phrase in their title. It occurs frequently in the news as well.
The phrase refers to the practice of setting boundries for children.
Mom: She is staying out all night and her friends are drinking heavily. I am worried about her.
Dad: You just have to use tough love and ground her until she has time to see how ill advised her choices really are.
A phrase indicating affirmation, enthusiasm or just general agreement.
Probably first used in the Midwest USA (Kansas City, St. Louis, Minneapolis etc.) in the early 70s where it was spoken by radio station DJs and was initially popular with high school and junior high school girls. It was spread primarily through TV and radio given that it was coined before the world wide web was in use. Now, occasionally it is heard world wide in the USA and the Anglophone Common Wealth. Although it is not a common phrase, it is usually understood, evidently, since it employs the widely recognised adjectival 'cool'.
Person A: We'll be there about 3 or 3:30.
Person B: Cool Bananas.