Abbott Elementary and It's Always Sunny in Philadelphia ... episode using the IASIP gif. A meme published by @HowlJackson portrays the character Charlie Kelly being his weird self around children.

The star of the FX series also admits he was initially hesitant about the crossover concept as 'It's Always Sunny in Philadelphia ... with something funny to do. Charlie Kelly fit so naturally ...

When “Abbott Elementary” creator Quinta Brunson mentioned the idea of a crossover episode with “It’s Always Sunny in Philadelphia” — fueled from a conversation with Rob McElhenney ...

The cast of It’s Always Sunny in Philadelphia made its way to ... The brief promo for the Jan. 8 crossover sees Charlie Day’s Charlie, Rob McElhenney’s Mac, Danny DeVito’s Frank, Kaitlin ...

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

Charlie learns to read, Dee impersonates Ben Franklin, and Frank fights raccoons. We don't quite know what's up with Dennis though.

Okay, so let's kick things off with a "who's who" look at our major players tonight: FXX's "It's Always Sunny in Philadelphia": Rob McElhenney (Ronald "Mac" McDonald), Charlie Day (Charlie Kelly ...