As the How I Met Your Mother cast prepares for Monday night's series finale, they made an appearance on Inside the Actor's Studio where a fan asked if Neil Patrick Harris and Jason Segel for a special favor. 

After the pair briefly sang the Inspector Javier and Jean Valjean duet, the  "Confrontation," on the Megan Mullally Show in 2006, the fan asked if they would reprise the performance. With almost no hesitation, they broke into the famous Broadway show tune. 

Perfectly executing the wordy duet, the duo brought the house down, as the happy audience gave them a standing ovation. 

The series finale of How I Met Your Mother airs Monday, March 31 at 8 p.m. ET on CBS.