The end-all to any argument, dispute, declination of sexual proposition, etc. Popularamong date rapists, but can be used whenever you have no response to a statement or question.
ex 1
guy: lets go to my room
girl: no, i should be going
guy: just let it happen...
ex 2
guy 1: hey i wrecked your car guy 2: WHAT?
guy 1: dude just let it happen
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.
Used in a conversation, when you want to indicate that the previous statement you made doesn't actually matter and that the listener can feel free to ignore the previous statement.
Also, if you use the word "this" instead of "that", then it could be used to preface the irrelevant claim you're about to assert.
"Just saying" is a synonym phrase of the same meaning.
Margaret: Which of those two women over there is your boss?
Julie: The one in the pink dress.
Steve: She's really hot! (Margaret and Julie turn to stare at him.) What? I'm just throwing it out there.