[This story is from one of my favorite newsletters, Now I Know. It has over 100,000 subscribers. Sign up for it here. -- Mark] If you're a four-year-old in the United Kingdom, you probably know who Peppa Pig, above, is. The anthropomorphic, snorting pig and her family are a mainstay of children's television there -- and, increasingly, elsewhere -- with unrivaled popularity throughout Great Britain.