Some phrases and words are annoying. Among my pet peeves are nounifications of verbs as in "My ask of you is..." but the worst is, "Just sayin'." Let's give it up, mmmkay?
Just Sayin' is meant to be a puckish little disclaimer to convey, "I have no vested interest in what I've just said. The preceding thought was meant only to be informative and, in fact, I might not even believe what I just said." Just sayin' is almost always used sarcastically and passive aggressively. It is frequently the last phrase in a sentence or a thought. There are 2258 Lexis hits for Just sayin' and an astonishing 1,940,000 Google hits. Many of the instances are in comments but clearly the pandemic is here.
From Rob Long's column in the National Review about Arlen Specter which ended, "Switching sides has gotten a pretty bad rap, I agree, but when you really dig down and think, really think, about it all, it's not really such a bad idea. Just sayin'."
From a comment by Jen in Astoria on an article about winemakers on the wine blog, The Pour, of the Times: When you say "extreme winemaker" I'm picturing some guy with questionable tattoos and piercings doing the initial grape mash by flailing around naked in it, to a soundtrack of either very bad techno or death metal. Just sayin'."
From a post on this blog about the similarity of Julia Allison and Judith Regan, "Yeah, we think that foxy, unstable publisher bears a striking resemblance to someone else we know. Not her actions or anything. God forbid!! No, just her looks. Who could it be? Just sayin'!"
It's hard to identify from whence the phrase comes or the first time it was used. But its risibility is clear.
If you didn't mean what you said or if there was no import to it, don't say it. Why say it? Don't say it. But worse than that, you obviously did mean what you said so don't veil it with pretending you didn't. Last month was the R-Word Month, during which the public was meant to avoid saying "retard" as an insult. Let's make this the month of not saying Just Sayin'. It's dumb and retarded. Just sayin'