S.A.D is an acronym you have unknowingly used many times.
It stands for 'Solitude and depression'
Person: "Are you S.A.D?"
Person 2: "yeah I am in solitude and I am also depressed."
When you are looking up the weather is going to be like in the following days and the weather in 2 days surprises you.
Person a: 'Damn dude, it's going to be extremely cold in 2 days'
Person b: 'Sounds like the movie "the day after tomorrow"'
Person c: 'That's the "the day after tomorrow effect"'