Just found these somewhere on google..

"Tag questions are something like negative questions. They are use when someone thinks he or she knows the answer but wants confirmation."
A question tag or tag question (also known as tail question) is a grammatical structure in which a declarative statement or an imperative is turned into a question by adding an interrogative fragment (the "tag").But you don't really love her, do you?This'll work, won't it?Oh you think so, do you?Well, I couldn't help it, could I?But you'll tell me if she calls, won't you?We'd never have known, would we?Oh you do, do you?The weather's bad, isn't it?You won't be late, will you?Nobody knows, do they?You never come on time, do you?You couldn't help me, could you?You think you're clever, do you?So you don't think I can do it, don't you? (British English)Shut up, will you!She can hardly love him after all that, can she?Nothing will happen, will it?