My favourite impossible bug was during a autonomous robotics course in which we had to design a small robot which would collect balls and move them within a tar

My favourite impossible bug was during a autonomous robotics course in which we had to design a small robot which would collect balls and move them within a target area using quite simple sensors. One of these sensors was a simple conductive sensor which sensed metallic tape on the floor of the arena. One of the teams had a freezing issue that they couldn't get to the bottom of, until they realised that it froze when their back roller (a sphere in a cage so it can rotate in 2 directions) went over the metallic tape. The theory goes that the moving lego parts generated static electricity which was then conducted somehow down to the metallic tape, which caused some fault in the single board PC we used. I wouldn't have believed it unless I'd seen it. Replacing the metal roller with a lego piece cured the issue.