If you think that the stereotype of Swiss people lacking a basic sense of humor is true, any contact with the Swiss Federal Administration will probably comfort you in your thoughts. Swisstopo, the Federal Office of Topography probably hosts some of the most boring people that live on this Earth.
However, a few of them seem to have developed a kind of taste for jokes and have hidden, throughout the years, all kinds of small drawings in the very serious maps of Switzerland. These were added mostly in very remote regions, where it will not influence anything for maps users, and all the drawings are hardly perceptible to the eye.
As the cartographers didn’t want to take any risk, which is another trait of the workers of the Swiss administration, they timed their drawings to the day of their retirement, thus not risking their job for an inaccuracy in the official maps.