Something you say to somebody when you want them to shut up. If somebody is taking something too far, or being cocky, politically incorrect, or annoying, you can say, "you're right, you're right." If somebody is trying to hard to prove their point and you don't agree, you can say it.
An insult used to call someone worthless and dysfunctional. Comparing them to a tool means that they aren't smart, are easily manipulatable, are an asshole and don't act like a proper human being.