Excuse me: What is this joke about?

The taxi driver passed the mountain road late at night, and a woman in white signaled to get on the bus. After getting on the bus, the driver looked at the co-pilot's messy long hair and slender nails, like black hole eyes, as if he had noticed something. The driver asked, are you a girl, not a person? The woman opened her bloody mouth and smiled strangely, saying, Ha ha ha, yes, I'm really not human ... At this time, the driver's face gradually changed, revealing sharp fangs, looking at the woman with blood-red eyes, and slowly saying, I'm not human either. The woman paused, put away her bloody mouth and gasped in surprise. The driver said slowly. The two men looked at each other, embarrassed and silent. The air was quiet, except for the sound of the taxi engine.