(sort of a spin-off)
I did – someone here posted a story about someone who died in a (somewhat dramatic) accident right out of high school. I didn’t know exactly who she was, but obviously we went to the same school. We PM’d and found that we did know each other, I’m pretty sure we were in Algebra II together.
And doggone it, she hasn’t aged a bit! 
Anybody else?
My nephew posted a family story and I knew from the location it had to be him. Nobody else would know that story and nobody else was living in Las Vegas. I looked up some of his other posts and knew it was him.
Hey, I know you! Remember that $5 you owe me?
Oddly enough two old co-workers from the same company are regular posters here. I’ve lurked for about 8 years now, and I remember them posting here from work then. It’s weird that I know so much about their lives. I even see these people out around town now and then and I almost feel devious that I know such personal things about them.
I just found out that one of the MMPers is a highschool friend. I began to get a spooky feeling as details converged, and asked her.
Yup.
So far - nope.
Who?! Fun!
I may or may not know Kilvert’s Pagan, as I’m realizing in a thread about the town where we both live!
There’s one poster who I suspect I may have met many years ago. But otherwise, no.
On the other hand, I ran into **ElvisL1ves ** last Sunday as I was on a bike ride!
(Not literally)
Me. 
I’m torn between humming It’s a Small World or the Twilight Zone theme.
I was watching Bob Costas do a sports show on HBO last weekend, and he used “snark” and “jump the shark” in the interview!
So, well, I believe I know of a Doper in real life.
It’s good if you combine them.
:Tries to imagine it:
Rilchiam and I turned out to be former classmates at a very small school.
What does it prove? Both of those terms are certainly not exclusive to Straight Dope.
Not in real life.
I was introduced to the SDMB by an online friend of long standing. I don’t recall what his user name was here, so I have no idea if he still posts or not - and I keep forgetting to ask him. (Da Bish, you around?)
I once recognized someone here as someone having a huge blowout in another community at the time (and being mocked via a third community that I belong to). The situation she was ranting about was rather distinctive, and she had a Pit thread going about it as well.
It’s unconfirmed.
There is a poster here from where I grew up and lived for about 20 years. Some things they have posted make me think that I know them, possibly went to school with them.
I am just too chicken shit to message them and find out.
:o
I keep expecting to run into my old college boyfriend here, but so far, no.
I did meet a woman I knew in college on another MB. Oddly, we are doing many of the same things, though we aren’t much alike.
A couple of years ago, I realized that I went to high school with a current poster. We hung out over the weekend and I expect to see her again Sunday.
I suspect my roommate from freshman year is on here somewhere, but I’m not sure.
If you are, hi Matt!
Not only that, they both are very common and pre-date the SDMB.
I should mention that my husband did run into a college buddy of his here. The friend recognized my husband’s username.