Might contain spoilers!
In the TV series Stranger Things, more particularly in S01 E08, in Will's house when the Demogorgon appears, just before that the lights blink, like an indication of it's arrival. Also Jonathan is shown telling Nancy the same thing -
Nancy: Did you hear that?
Jonathan: Don't worry. It's just the wind. My mom, she said the lights speak when it comes.
The blinking of lights has also happened earlier. What is the theory behind the lights blinking when it comes?