Originally, Aunt Jackie was supposed to watch The Chipmunks after Dave broke his leg, but she fell down an escalator at the airport and had to go to the hospital, leaving them in Toby's care
Jackie is a kind, elderly lady in a wheelchair. She lives with her grandson Toby, who she claims is "living with her until he figures out what he wants to do with his life, and so far that involves going 'pew pew pew' with his thumbs all day." She is rather strict with Toby.
The whereabouts of Toby's parents are unknown.