The protagonist of the series is Andy Larkin, a mischievous 12-year-old preteen and the self-proclaimed "world's greatest prankster." The show follows him as he tries to perform incredibly well-thought-out and elaborate practical jokes, or pranks, on people. He lives in the fictional town of East Gackle. He constantly breaks the fourth wall when the screen freezes. Andy's best friend, Danny Pickett, helps him out with almost every prank. His enemies include his older sister, Jen Larkin, and the bullies Peter Lik and Andrew Leech. Andy has a crush on a girl named Lori Mackney and usually tries to impress her. The show is based on Australian author Andy Griffiths' children's series of "Just!" books, which were illustrated by Terry Denton.
