20 Mind-Blowing Facts You Never Knew About Pixar
12. To Record Boo's Lines, The Director Chased Her Around The Studio
While a lot of times kids in movies are actually voiced by adults, Pixar wanted Boo to sound authentic, and so they got an actual little kid to do the voice in Monsters Inc.
Boo was voiced by Mary Gibbs, who was just two years old at the time. You can imagine it wasn't exactly easy to get a two year old to sit in a voice acting booth all day, so to capture her dialogue and sounds, director Pete Docter would chase her around the studio holding a microphone. They'd use puppets to talk to her and have her mom tickle her to make her laugh or take away candy to make her cry; almost all the emotions you hear from Boo in the movie are totally real.
Gibbs' dad was actually a storyboard artist on the movie, and was originally used for drawings and some temporary dialogue. The director ended up liking Gibbs so much they used her for the final film.