Rob McElhenney, Glenn Howerton, Kaitlin Olson, Danny DeVito and Charlie Day act during a dance scene on the set of “It’s Always Sunny In Philadelphia” on May 23, 2007.

Danny DeVito, left, and Charlie Day, photographed at Fox Studios in Los Angeles this month, are back for Season 17 of “It’s Always Sunny in Philadelphia,” which turns 20 this year.

Danny DeVito, left, and Charlie Day, photographed at Fox Studios in Los Angeles this month, are back for Season 17 of "It's Always Sunny in Philadelphia," which turns 20 this year.

Speaking with Collider, DeVito brought up the BTS Gang’s real-life gag when asked about any Always Sunny situations that skirted the line of going too far. He started his story with: ...

The brainchild of Rob McElhenney, Charlie Day, and Glenn Howerton (collectively known as RCG), It’s Always Sunny, which premiered on FX on Aug. 4, 2005, introduced "The Gang," a gaggle of self ...