EXCLUSIVE: Nathan Fillion and Alan Tudyk Dish on 'Con Man,' 'Guardians of the Galaxy Vol. 2' and Wild Comic-Co

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When it comes to Comic-Con, Nathan Fillion and Alan Tudyk are essentially gods among men for their work on some of geekdom's most beloved properties, which is why they've gotten some particularly strange autograph requests in their time.

The former Firefly co-stars -- who also created the quasi-autobiographical web series Con Man, about being fan convention superstars -- spoke with ET's Ashley Crossan at this year's Comic-Con in San Diego on Saturday, where they opened up about the weirdest things they've ever been asked to autograph.

"A foot," Tudyk recounted. "[Which] he took off and put on the table."

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While Fillion, whose popular mystery procedural series, Castle, recently came to an end after eight seasons, didn't mention getting any prosthetic limb requests, but agreed that people ask to get their body parts signed all the time.

"People say, 'Hey, would you sign my arm?' or something like that. [I'll say], 'yeah, no problem, I totally will.' And then they'll come back and say, 'I had it tattooed in!'" the 45-year-old actor recalled. "I wish I had known that. I would have used a different pen. I would have been much more careful."

"I would have actually signed my name!" Tudyk quipped.

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In Con Man, Tudyk stars as Wray Nerely, an actor who starred in a short-lived but beloved sci-fi series (sound familiar, Firefly fans?). Wray's co-star on the show, Jack Moore (Fillion), has gone on to become a huge star while Wray's been relegated to making paid appearances at sci-fi conventions and comic book stores. The show explores their relationship and how life has changed for the show’s cast and crew since going off-air.

The second season of the originally crowd-funded series premieres later this year, but it's not the only big project the two stars are looking forward to. Tudyk was recently cast in the upcoming Disney animated film, Moana, while Fillion just finished shooting his appearance in the highly anticipated Guardians of the Galaxy Vol 2.

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"If [director] James Gunn calls you up and says, 'Would you do this little thing in Guardians for me?' you say, 'Yes.'" Fillion explained.

While he's is rumored to play Simon Williams, a.k.a. Wonder Man, Fillion refused to comment on the fan speculation.

"If James Gunn says, 'Hey, though, would you keep this really hush hush? And not say anything about it?' what would you say?" he continued, opting to keep quiet.

For more on Guardians of the Galaxy Vol. 2, check out the video below.

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