“I said in an interview that my mom’s favorite show was The Big Bang Theory,“ Thornton recounts in the above featurette from The Big Bang Theory: The Complete Eighth Season DVD (available Tuesday). “So [exec producer] Chuck Lorre got a hold of my manager and said, ‘Would you consider doing a guest spot for your mom?'”
Lorre had Thornton at “mom” and that paved the way for the Fargo actor’s surprise appearance as a urologist crushing on Penny in Season 8’s “The Misinterpretation Agitation.”
Press PLAY above for an exclusive behind-the-scenes look at Thornton’s episode. Bonus: Find out why Kaley Cuoco-Sweeting initially didn’t believe news of the A-lister’s Big arrival.