What might be an innocent (or not) reply could potentially go not just to your friends, and their friends, but also to the entire readership of Iltalehti.
We can get into an interesting argument about whose fault this this and whether the person posting should have read that comment about the potential readership, however discussing fault and appointing blame isn't too helpful as we've discussed earlier in an article about understanding accidents.
None of the 3 parties involved here: Facebook, Iltalehti and the writer of the comment are entirely to blame nor entirely innocent, but just like the pilot who let his airspeed decay and crashed the aircraft, we have an overall education and situation awareness problem that is going to be very difficult to change.
I'm not even advocating not posting to Facebook, but just be more aware of where comments are going to end up in addition to what you think your Facebook privacy settings are.
Note for non-Finnish speakers: apparently hair pins are being used the wrong way round...you can put the above article's URL into Bing or Google to translate.
Aside: first time I used Bing translate, it worked perfectly....though it did translate Finnish to...Finnish....
Secondly, regarding the above article on hair pins...it reminded me of a quote from Douglas Adams' Hitchhikers Guide to the Galaxy:
The sign said: Hold stick near centre of its length. Moisten pointed end in mouth. Insert in tooth space, blunt end next to gum. Use gentle in-out motion.
"It seemed to me," said Wonko the Sane, "that any civilization that had so far lost its head as to need to include a set of detailed instructions for use in a packet of toothpicks, was no longer a civilization in which I could live and stay sane."