Haha, I lived in Munich for many years and still got burned. I was on the wrong train and noticed after a single station along the wrong branch. No biggie, got

Haha, I lived in Munich for many years and still got burned. I was on the wrong train and noticed after a single station along the wrong branch. No biggie, got off the train and hopped on the next one back to the station I came from. Got fined because it turned out my ticket only allowed travel in one direction, not backwards. Most expensive kilometer of my live. Had I known, I had walked the short distance between the stations.