Green’s Dictionary of Slang

Chatty Cathy n.

[trade name of a pull string ‘talking’ doll manufactured by the Mattel toy company 1959-65]

(US) a very talkative girl or woman.

1998

D. Lehane Gone, Baby, Gone 76: [E]ven in the best of times, she was far from a Chatty Cathy in the morning.