The Bright Side 🍀 on Instagram: "In Monsters, Inc., Boo is the only human child in the film and one of the most endearing characters. Behind her voice is Mary Gibbs, a little girl who was only 2 or 3 years old at the time and was not an actress. Unable to read a script or sit still in a studio, the Pixar team came up with a brilliant idea: let her play freely! 🤩 Mary ran around the studio as if it were a playground, while the team followed her around all day with a microphone. Her laughter, he