Used by someone as a way to soften a direct insult by saying it was just a joke, although the person doing the insulting still means the insult after the Just kidding! has been said.
Reggie: "Bob, you're such an asshole!"
Bob: "What?"
Reggie: "Just kidding!"
Bob: "Oh, ok."
Bob now doesn't feel he's been insulted, because he was told that it was a joke, but Reggie still means what he said.
2. You were actually serious but decided what you said was actually very mean
3. You were actually serious but since that person took what you said offensively you cover it up by saying" just kidding"
4. When you try to confess to something and that person is either laughing at you in disbelief or just very angry you cover it up by saying just kidding
An expression used (typically through text) as a way to find out if the person you are talking to is okay with what you just said. If they are okay with it, then the conversation can continue to build. If not, then you can confirm it was only a joke.
John: You, me, and your girlfriend should have a three way.
John: ...just kidding?
Ben: That would be really weird.
John: *hesitation* Yeah I know.