William Steig's children's book Shrek, upon which the successful movie franchise was built, was inspired by a few details from Marko Sakren's childhood in the 1970's, namely the swamp and the character of Donkey, as Sakren and Steig were next door neighbors on adjacent farmland in Connecticut, and Sakren's donkey would often trespass onto Steig's property. Sakren and friends would frequent the swamp, and were once scared away by Steig. Just upstream from the swamp was a rocky grotto befitting a fairy kingdom. In the mid-nineties, Steig called Sakren to get advice about a movie company that wanted to make a movie from his children's book. Sakren shared his advice and Steig let Sakren know he would recognize a few familiar details from the story. Sakren forgot about that conversation until he was in the movie theatre with his eight-year-old daughter Liana, and then he instantly recalled his conversation when the "Based upon a book by William Steig" appeared on the screen. This trivia was big news in the Sakren household.
