When the narcissistic gang from "It’s Always Sunny in Philadelphia" visited the "Abbott Elementary" school in a crossover episode earlier this year, audiences got to see the two Philly TV universes collide in hilarious ways — all while keeping the episode PG for "Abbott’s" more family-oriented viewers.

The actors discuss playing best friends and roommates on FX's long-running comedy, which kicks off its 17th season Wednesday, and why "whenever Charlie does something, it titillates Frank."

Eric Biermann was the brother of Todd Biermann. Todd is the director of It’s Always Sunny in Philadelphia Season 17 Episode 1. He has been associated with the sitcom since 2012 and has helmed its 17 episodes across various seasons. Todd has also worked on several other acclaimed shows like Ghosts, Mythic Quest, Superstore, and Black-ish.

In an encompassing New York Times feature on the long-running sitcom, the show's creator says he sought to explore the humor in selfish people who are never there for their friends.