Musician and comedian Reggie Watts helped fellow late night talk show host Conan O'Brien celebrate his triumphant return to New York City on Halloween night by winding down Mondays' 'Conan' show with a rousing rendition of Thin Lizzy's 'The Boys Are Back In Town.'

O'Brien -- who taped his 'Late Night' show in New York for more than 15 years before splitting town for Los Angeles in 2009 to helm 'The Tonight Show,' a gig he ultimately lost -- was back in town to tape his new show, 'Conan,' in the Big Apple.

"It's great to be back here in the place I never left," Watts muses as he begins tickling the keys of a baby grand. "Ladies and gentleman, in tribute of music, and of Conan's return, please enjoy." He then begins belting out 'Boys' over sparse piano chords and keyboard accompaniment, his deep and delicious voice more than holding its own in comparison to that of late Lizzy singer, Phil Lynott.

As he comes to the chorus, Watts -- dressed decidedly dapper in a crushed purple velvet tuxedo, his big Afro strikingly similar to Lynott's (it was, after all, Halloween) -- gets up from his chair, the camera pans back to reveal a full band complete with horn section, and the everybody kicks of the jams!

Welcome back, Coco.

Reggie Watts Performs Thin Lizzy's 'The Boys Are Back In Town' On 'Conan'