It’s always busy for the It’s Always Sunny in Philadelphia cast.

The 'Abbott Elementary' EPs talk jokes cut from 'Always Sunny' crossover, including backstories for Frank and Mr. Johnson.

Compendio: Frank is established as Dennis and Dee’s father when he first appears in Season 2 of "Always Sunny" — though the audience later finds out that he is not their biological father.

Slimy, vaseline-covered and crawling out of a couch naked, or waving a gun around and firing wildly — those are the two images that tend to come to mind when you think of Danny DeVito’s character Fran ...