The cast members of "How I Met Your Mother" appeared in the "Late Show with David Letterman" on Monday, February 18, to read the list of "Top Ten Surprises in The Final Episode of How I Met Your Mother." One series finale surprise, according to actress Cobie Smulders in the Mail Online report, will have the entire HIMYM gang naked for some reason.

"How I Met Your Mother" fans have a lot of questions on what will happen in Season 9 but cast members Jason Segel (Marshall), Cobie Smulders (Robin), Josh Radnor (Ted), Alyson Hannigan (Lily) and Neil Patrick Harris (Barney) only gave silly hints in the late night show. Another series finale surprise teased during the show came from Alyson Hannigan.

"To find out how Ted met the Mother, send a self-addressed stamped envelope and $500," Ms Hannigan stated during the list read. The HIMYM cast members also filmed an appearance in James Lipton's Bravo show last Sunday, February 16.

Credit: YouTube/Late Show with David Letterman

An unnamed source dished to Us Weekly that the cast's appearance made the attendees really excited while taping at the Michael Schimmel Center for the Arts at Pace University in New York City. Mr Lipton, 87, discussed the HIMYM stars' childhood and biggest TV or movie roles before signing up in CBS' successful sitcom.

Neil Patrick Harris acknowledged his TV show Doogie Howser M.D. for making him a famous star but admitted that being a child star made it difficult for him to go to school. Actress Alyson Hannigan looked back at her roles in the TV series "Buffy the Vampire Slayer" and the 1999 comedy film "American Pie" where her character's "This one time, at band camp" line became famous.

As for Jason Segel, the actor recounted his nude scene with co-star Kristen Bell in the comedy film "Forgetting Sarah Marshall" back in 2008. The 34-year-old actor revealed that he never told his mother about that movie scene until she finally watched the film in a theater.

While taping the entire interview, an insider shared that the cast members' love for each other was very obvious. "It's hard to imagine a cast that seemed closer and more comfortable with each other. The way they would all lean in to support each other, but allow each other time to speak," the insider divulged.

"How I Met Your Mother" Season 9 airs Monday nights at 7 pm central time on the CBS network. The comedy series is scheduled to return from a short break on February 24 with Episode 18 titled "Rally" while the two-part finale episode "Last Forever" is set to air on March 31.

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'How I Met Your Mother' Season 9 Spoilers: Final Episode Details on CIA-Level Lockdown, Cristin Milioti Still Has No Idea What The Mother's Name Is - [READ]

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