An old lady forgets her drivers licence at home. She travels down a one way street the wrong way. She does not stop at stop signs, or stop for people crossing the road. A cop is watching her do this and he does not give her a ticket. Why didn't he give her a ticket?

Why this works

This riddle plays on the assumption that the old lady is driving a vehicle, which leads you to expect traffic violations. However, the twist is that she is actually walking down the street. Since pedestrians don’t need a driver's license, can walk in any direction on a one-way street, and are not subject to the same rules as drivers, the cop has no reason to issue her a ticket. The clever misdirection encourages you to picture a scenario involving a car rather than considering the possibility of her simply being a pedestrian!