Will Ferrell Serenades Letterman With 'Send In The Clowns' (VIDEO)

08/03/2010 11:56 am ET | Updated May 25, 2011

Appearing on Letterman (in his "summer suit" no less), Will Ferrell did what he does best...sing show tunes. Wait, what?

When asked about his upcoming projects, Ferrell responded, "Unless you've been living on the moon, Dave, you know I'm replacing Catherine Zeta Jones in a 'A Little Night Music.'" And to prove any doubters wrong, Ferrell grabbed a mic, got in bed, and sang a powerful rendition of "Send In The Clowns."