As I did some mapping of planet Earth during the last week (read here what planet Earth is, if you don’t know :) ), I temporarily set JOSM to connect to the OSM server. Actually, I mapped all buildings with housenumbers and special addresses in Keitum, Sylt island, Schleswig-Holstein, Germany.
Yesterday I continued in OGF but for some stupid reason forgot to switch back to the OGF server. As I had loaded a locally saved .osm file I didn’t recognize this until I uploaded the changesets and got completely strange JOSM error messages. The changesets have already been reverted in OSM (or are going to be soon) but for a short time, northern Kalmian stuff appeared within the forests between Moscow and Yaroslavl in Russia. Here you can see at least the railway station:

But finally, after a bit of late night work yesterday, here it is now, the small coastal town of Brenta, Assen canton, Nordland region, Republic Kalm.
Happy mapping! joschi81
Discussion
Comment from Demuth on 26 February 2016 at 14:38
Ha ha! I wonder if any Muscovites or Yaroslavlites (is that the right demonym?) on this so-called “Earth” noticed that suddenly there was a brand new railway station named Brenta (spelled with Roman letters) on their OSM-generated maps?
Comment from thilo on 26 February 2016 at 18:44
Muahahaha! The world will be Tlön.
On a more serious note. I recommend that you make a copy of the JOSM configuration directory. On Windows 7 for example, it’s in “C:\Users\USERNAME\AppData\Roaming”. Then you can start JOSM with from the command line, e.g. like this (or even better, write a small script for this):
java -Djosm.home=%APPDATA%\JOSM_OGF -jar “C:\Path\to\JOSM\josm-tested.jar”
There are tow main advantages: