Premise: That '70s Show is an American television period sitcom that originally aired on Fox from August 23 , 1998 , to May 18 , 2006 . Thomas B. Kin Chong ( born May 24 , 1938 ) is a Canadian-American comedian and actor , who is known for his marijuana-themed Cheech & Chong comedy albums and movies with Cheech Marin , as well as playing the character Leo on Fox 's That '70s Show .
Hypothesis: Tommy Chong was only in BBC sitcoms.
Label: CONTRADICTION