Fridge Logic is a somewhat meta foreshadowing. Something that isn’t ever explained directly in a work but you put two and two together and suddenly you realize something deep about what the writers/creators were/are planning. It doesn’t always matter to the plot (therefore, isn’t foreshadowing) but it enriches the work.
The name comes from the fact you don’t realize it until you get up and open the fridge.
What are your favorite examples of Fridge Logic (sometimes called Fridge Brilliance)? What are your own points that you hope people will stumble upon when they get to the fridge?