'How I Met Your Mother' Stars Tease Finale 'Surprises' on Letterman's 'Late Show' (Video)

Josh Radnor, Jason Segel, Alyson Hannigan, Cobie Smulders and Neil Patrick Harris trot the sitcom's final episode Monday evening opposite NBC's new "Tonight Show" unveiling.

David Letterman welcomed the How I Met Your Mother cast for the Late Show's Top 10 centered on the CBS sitcom's series finale.

Josh Radnor, Jason Segel, Alyson Hannigan, Cobie Smulders and Neil Patrick Harris presented the list Monday evening with what viewers can expect -- sort of -- from the March 31 swan song. In a minute-long preview released prior to the episode, the How I Met Your Mother stars gave a glimpse of three of the 10 finale "surprises."

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10. "Finale? We've been canceled?!" -- Segel

9. "The real father: Frank Sinatra." -- Smulders

8. "Fairy tale wedding with the cast of Blue Bloods." - Radnor

7. "You know that bar we hang out in? We buy it and turn it into a Duane Reade." - Hannigan

6. "Together, Velma, Ted, Daphne, Shaggy and I crack the case of the arsonist." -- Harris

5. "It's on NBC." -- Segel

4. "For some reason we're all naked." -- Smulders

3. "Someone finally points out that I don't sound like Bob Saget." -- Radnor

2. "To find out how Ted met the Mother, send a self-addressed stamped envelope and $500." -- Hannigan

1. "Biggest surprise? We're going off the air and Letterman's still got a show." -- Harris

Letterman's How I Met Your Mother booking comes on a night NBC rolls out the high-profile hosting debut of Jimmy Fallon on the network's storied late-night franchise, The Tonight Show. Letterman referenced Fallon's start in his monologue, although he didn't mention his competitor by name. "First thing this morning, I get a call from my mom," Letterman said. "She says 'David, did something happen to Jay?' What am I gonna do?"

Watch the preview below.

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