To Know Better

I suggest you stay away from explaining idioms. They are too tricky for both children and other learners of a foreign language. "You know better than that", you never even considered this one. It seems so easy, in any language. It's not an idiom, idiot, it's a universal phrase. Shy around a drunken bonfire? You know better than that. Take more than "a penny"? You know better than that. Reading a personal profile? You know better than that. Fall in love with the hand who holds your back? You know better than that. Once a turk, always a turk. You know better than that. Writing nonfiction in the form of a fable. You know better than that. Whispering truth in a crowded bar? Ya, to know better.