When something in the story or movie is unexpected
a fire house is on fire
The good guy is the bad guy
The dump truck was clean
Examples of Situational Irony
It say on the building "smoking tabcco" then on the sign next to it says "rated number one in the state
The car is trying to sell five hour energy and the wo/man is asleep in the car
This is when what actually happens is the opposite of what's expected or appropriate.