The crew is mostly happy to be there, until Dennis (Glenn Howerton) notices the cameras filming them. Ava (Janelle James) tries to dismiss it, saying, "We have like a Vanderpump thing going on ...

The Abbott Elementary & It's Always Sunny In Philadelphia crossover had some ridiculous rivalries, but Charlie got a surprisingly uplifting subplot.

and Glenn Howerton’s Dennis scurrying away suspiciously after the gym’s scoreboard crashes to the floor. “It was kind of a joke at first, that the two shows should cross over,” he said.

It might be always sunny in Philadelphia, but that doesn't mean there aren't some clouds about to hit Abbott Elementary school. But Dennis isn't having it. "No, I don't think so," he says. "I know ...