Have you ever wondered if you came across another member of the site and didn't know it while in your daily life. The question. Have you meet some one before that you didn't know was from LPSG.
I think the poster is trying to find out if anyone has ever met or seen a member of the forum without intentionally meeting up. In other words, I see you on the street and recognize your picture from the site.
I'm not sure how much this counts, but a local member here came to our first meet-n-greet, we met and had a brief chat, then he left. We didn't exchange numbers, and all in all he left a neutral impression. A year or so later I discovered that he was very chummy with my new roommate and we actually became much friendlier.