Trivia: When Brennan (played by Will Ferrell) and Dale say, "Say your favourite dinosaur on 3", on the shelf there is a sign that reads 'Hugalo's Pizza', which is the pizza parlor that Will Ferrell worked at in Talladega Nights: The Ballad of Ricky Bobby.
Trivia: The name of the bully in the playground is Chris Gardocki, which was also the name of a punter who played in the NFL for the Cleveland Browns.
Trivia: Mary Steenburgen plays Will Ferrell's mother in the movie, even though in real life she's only 14 years older than him.
Trivia: The song Brennan sings at the end is called "Por ti volare" and it's the same song that his rival Jimmy McElroy skates to at the beginning of Blades of Glory that released the year before.
Answer: I doubt it's a person. Jack likely refers to Jack Daniel's, and a handle is usually referred to as a half gallon. Hence the name Jack Handle.