One time, a girl in my family went into the toilet and shut the door. Her father followed her and backed into the toilet
through the closed door, as if he were a ghost. The girl then came out as usual, opening the door, but as soon as he had left the door became shut again. Unless he was hiding behind the door there was no sign of the father in the toilet. A moment later the door opened and out came the father.
They must have both decided to use the facilities at the same time.