And exclamation when someone suddenly realizes something isn't right.

a phrase used when one is confused with what is happening in a situation, or has not heard what another person is saying

What you say when one (or more) of your friends is talking to you, and you are daydreaming about something completely unrelated. Usually said after saying something else, completely random.

Term used on the Internet to indicate confusion about, and often to point out a contradiction within, something someone else has said.

Said often after coming to the realization that what someone has just said is either offensive to you, or someone you care about.

A way of indicating that the thing you or someone else just said makes no sense.

A phrase used to back the conversation up when you realize you weren't listening. You caught the ice cream end of the conversation,and oops, you wish you had heard the meat and potatoes. It could be important, so you use this phrase to try and sneak by the fact that you were thinking about dirty pics and bacon cheeseburgers while your friend was pouring their heart out. Hopefully they're so distraught they'll rewind and repeat without noticing.