Tonight is going to be a sad, yet fulfilling, night for fans of the hit show "How I Met Your Mother". After nine seasons, the series finale of the show will air tonight on CBS.

Because of this, the cast has been making their rounds to talk about the show, and last week, the entire cast was on "Inside The Actors Studio". One of the audience members asked Neil Patrick Harris and Jason Segel to sing a duet, the two obliged, and the result is amazing.

During the "How I Met Your Mother" episode of "Inside The Actors Studio," the audience member asked the duo to sing "Confrontation" from "Les Miserables" since "it's coming back to Broadway". The two apparently used to sing the song together quite often (including an appearance on "The Megan Mullally Show" back in 2006), but according to castmate Alyson Hannigan, they hadn't sung it together "in a long time!"

Without even the briefest hesitation, the guys launched into an awesome rendition. Seriously, it's great. Watch the whole clip above.