If you think the stereotype of Swiss who have no sense of humor is true, all contacts with the Swiss Federal Administration will probably comfort you in your thoughts. Swisstopo, the federal agency for topography, is likely to host some of the most boring people living on this planet.
However, a few of them seem to have developed a kind of joke flavor and, over the years, have hidden all sorts of small drawings on very serious maps of Switzerland. They were mostly added in very remote areas where it does not affect map users, and all the drawings are barely noticeable to the eye.
Because the cartographers did not want to take any risk, which is another feature of Swiss administration employees, they timed their drawings to their retirement date, so they did not jeopardize their jobs with inaccuracies in official maps.