I believe that is the case, but am not certain.

used after a statement to indicate an emphatic or ironic negative

(chiefly Britain, idiomatic) I am mistaken; I thought that what I said (or wrote) was true, but I have just realised that it is not.

A phrase used in response to a question or command in which the target person does not know the answer to or how to respond.

Indicates that the speaker is not understanding the current subject or situation.

A request for information.

(idiomatic, dated) An exclamation of great surprise.

(idiomatic) An exclamation of great surprise.

Expression of hatred, or intense disdain or dislike directed at someone. Some might invoke this phrase without literal implication, such as unselectively and uncontrolledly directing the phrase to innocent surrounding people as a result of difficult life circumstances, or jokingly in reponse to being pranked. Such uses should be avoided, however.

(derogatory, Internet slang) You are stupid; said as if lowering oneself to an equally moronic state of mind.