Couch Gag

Every episode of The Simpsons opens with a variation on the same theme. The final part of this has become known as the Couch Gag. 

From Joel A. Sutherland:

Our kids were bored after four weeks of social isolation. My wife and I cleaned the basement and wondered what we should do with our old Simpsons Halloween costumes. One of these problems solved the other. The end result was this video.