Mark Hamill paid a virtual visit to “The Tonight Show” on Thursday to promote his new role as the voice of Skeletor in Netflix’s “Masters of the Universe: Revelation”.

Host Jimmy Fallon, however, is a huge fan of Hamill’s work in the “Star Wars” franchise, and wanted to know about his surprise cameo in the second season finale of “The Mandalorian”.

Describing the scene as “one of the coolest TV moments of the year,” Fallon asked how they were able to pull it off without ruining the secret.

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“Talk about unexpected!” said Hamill.

“I had finished playing that part. I never expected to do it again,” explained Hamill, who seemingly said goodbye to the character in “Star Wars: The Rise of Skywalker”.

“I thought if they ever told stories of Luke in that period, post-the originals and pre-sequels and pre-sequels, they’d get an age-appropriate actor,” Hamill explained. “So when Jon Favreau and Dave Filoni told me what they wanted to do, I was just stunned.”

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Given the “The Mandalorian” is set around the time of 1983’s “Return of the Jedi”,  Hamill is de-aged via CGI in order to appear younger.

“One of the main things with ‘Mandalorian’ is you are sworn to secrecy. I can’t even talk about it with my family, even now,” he joked.

However, Hamill revealed that a new special focusing on the Season 2 finale of “The Mandalorian” will be arriving on Aug. 25, which he promised will “answer a lot of your questions.”