My dad used to serve in the military. Their barracks were situated in an area that had once been a mass grave during the Second World War. Later, it was filled in, and buildings were constructed, serving as a military base. In the barracks, my dad shared a room with three other soldiers. They had bunk beds, and there was a ceiling light with a pull cord switch located about two meters away from the nearest bed.
One night, as everyone was settling into their bunks, they forgot to turn off the light. Someone said, "Who's going to turn off the light?" Just as the words were spoken, the light went out. They assumed it was a power outage due to unstable voltage and went to sleep. The next morning, when they woke up, they found that the light had indeed been turned off. They had no explanation for who or what might have caused it, leading them to wonder if a passing ghost had been responsible.