Young Sheldon EP Reveals Big Bang Alum's New Role in Season 5 Finale — Plus, Watch a Sneak Peek

Young Sheldon‘s future father-in-law will pop in for a very peculiar guest spot during Thursday’s Season 5 finale (CBS, 8/7c).

As previously reported, Penn and Teller will guest-star on the Big Bang Theory spinoff. However, Teller won’t reprise his role as Amy Farrah Fowler’s dad Larry. Instead, he’ll play one half of dermatological duo Acne and Pus. Allow us to explain…

In the episode, titled “A Clogged Pore, a Little Spanish and the Future,” 12-year-old Sheldon (played by Iain Armitage) struggles to cope with the first signs of puberty. Upon getting his first pimple, Penn and Teller appear as Acne Vulgaris and his silent sidekick (as seen in TVLine’s exclusive sneak peek above).

“We thought it was a fun idea to personify the pimple, so we were thinking about who would be right for Acne Vulgaris,” series co-creator Steve Molaro tells TVLine. “When we landed on Penn, he seemed so perfect, and it’s hard not to think of Teller when you think of Penn. Once Penn agreed to do it, we circled around to say, ‘How would you guys feel about doing it together, as Acne and Pus?’ They were very into it, and just a delight to work with from beginning to end.”

Teller on The Big Bang TheoryAnd if Teller had any hesitation about taking on a new role in the Big Bang universe, he certainly didn’t voice it to Molaro. “He knew what it was, and I think he knows this is set in the past,” the EP says with a laugh. “It’s a [different set of] characters here, and you know it’s Penn and Teller.”

As the boy genius stares down the barrel of adolescence, the rest of the Cooper family is dealing with a myriad of crises. Mary and George Sr. are on the hunt for new jobs, while Meemaw takes soon-to-be teen dad Georgie on a business trip across the border.

“We were attracted to the idea that something as small and simple as a pimple could cause such psychological torment for him,” Molaro says. “It’s interesting to see the onset of puberty, and to touch on Sheldon’s feelings about all the problems that the adults are having around him. Now that he’s becoming an adult, is this what life has in store?”

Watch Teller’s return to the Big Bang universe above, then hit the comments with your reactions to Young Sheldon‘s latest Easter egg.