I see this all over the ‘net. People post something blunt, then add "Just sayin’". I know you’re saying it, you just said it. 
What does that mean?
It’s a way of deflecting blame for your bluntness…Sort of like “Don’t blame the messenger.”
It’s not always meant to be taken seriously, either - some people use it as a “get out of jail free” card, others of us indicate that our outrageous statements were not dead serious.
Here’s the facts, but I’m not drawing any conclusions.
Right - sort of “don’t mean any harm, just throwing it out there.” Also used as an apology for a digression, a way of saying “apropros of nothing.”
I woulda thought everyone knew this. Just sayin.
How about people exclaiming “Now that’s what I’m talkin’ about!” when in fact they weren’t saying anything at all.
…well, you’ve at least drawn the conclusion that the person you’re saying this to may not have drawn the right conclusion.
It’s a gentle form of objection.
Often times it’s used in a sort of passive-agressive way, something like, “there are obvious and uncomfortable implications that follow from what I just said, but I’m specifically not explicitly saying them.”
For example, “Bill sure seemed to have a lot of extra spending cash right after that brand new computer went missing from the storeroom. Just saying.”
When I first encountered the phrase, it was in the context of two men talking about something. They are in agreement, and when one says something that closely matches his train of thought, the latter says ‘That’s what I’m talking about!’
Next, two guys are talking about something (women, cars, etc.). As they talk, an example of their conversation is seen. (i.e., a woman or car or whatever that fits their conversation passes.) ‘That’s what I’m talking about!’
Lately it seems to be a general interjection that doesn’t have anything to do with talking about anything. But it sounds cool.
Just sayin’.
“Just sayin’” = “I don’t want to make a big deal of this, but I want to make sure you’re aware of it.”
Or there’s the extended version (which is used a bit tongue in cheek), which is along the lines of, “not that I’m sayin’… I’m just sayin’”.
it’s nbd, js
Here is how I would translate it.
“I am making a simple statement of fact based on my observations. Although stating those facts may sound like I’m trying to imply that I’m passing some sort of judgment, or tell you what to do–I’m not. I’m just presenting facts, so there’s no reason for you to get pissed off.”
In practical use, it’s very similar to saying, “No offense” when you have just said something offensive.
Example.
Two people are in a car and approach a red light to make a right turn. The intersection is clear; there is no cross-traffic. The driver does not immediately turn.
Passenger: “It’s legal to make a right turn on red in this state.”
Driver: Dirty look.
Passenger: “Just sayin’.”
Sort of like “Bless her heart.”
I agree it’s a way to say something offensive and then try to take the “offensiveness” off of it, or absolve you from the blame of making an offensive statement
For example: Homer Simpson:
I think this is the closest. It seems to me, the phrase when used on these boards often means, ‘here’s a fact (that disputes the general discussion) regarding the poster/idea in question, but don’t think that I like or support him/it’.
Poster A: Poster B is a dumb shit who wouldn’t know a thing about politics if it bit him on his ass!
Posters C through Y: We agree.
Poster Z: In this thread (link), he did predict Obama’s election in 2007, just sayin’.
I’ll use it to mean “Based on your current conversation or action, I think you may be ignoring or overlooking something. I don’t know. You might have already considered it. You might not care. But I don’t want to have said nothing in case it does actually matter.”
Also, not all passive behavior is passive aggressive.
Unfortunately they don’t. That’s why you have to add "Know what I mean?’ after it.
Really. How can the OP have gotten this far in life and yet be baffled by this extremely common and intuitively self-explanatory expression? Just sayin’.