The Dayman Cometh: Watch ‘It’s Always Sunny’ Actor Charlie Day Join Portugal. The Man In L.A.

Portugal. The Man have been playing the song “Dayman” from the television series It’s Always Sunny In Philadelphia since at least 2014. “The Dayman” sub-character and song were portrayed and sung by actor Charlie Day, first appearing in an episode in 2007.

“The Dayman” was the subject of the 2008 episode The Nightman Cometh, with the song again sung by Day and featuring the opposing Nightman character. According to Setlist.fm, Portugal. The Man has performed “Dayman” over 120 times since 2014, including last night at the Hollywood Bowl in Los Angeles.

“Scott Marder and Rob Rosell wrote the episode and the lyrics: ‘Dayman, fighter of the Nightman, champion of the sun / He’s a master of karate and friendship for everyone,’ which are just the worst fucking lyrics ever,” Day’s co-star/co-creator Glenn Howerton told GQ. “Which is exactly what we wanted.”

Charlie Day emerged at the end of the evening’s performance to join PTM on piano and vocals for a triumphant performance of “Dayman.” Day’s appearance followed “Weird Al” Yankovic joining PTM for their recent collaboration, “Who's Gonna Stop Me.” Acclaimed singer-songwriter/actor Paul Williams also made a cameo during Sunday’s concert.

Watch “Dayman” and “Who’s Gonna Stop Me” via audience-shot video footage from last night in L.A. below: