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The Big Bang Theory: The Truth Behind Billy Bob Thornton's Season 8 Stint

If you delighted in seeing Billy Bob Thornton pop up on The Big Bang Theory last season, you can go ahead and thank the Oscar winner’s mother, Virginia.

“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.