Season 4, Episode 10
The family are seemingly frustrated with the fact that baby Maggie is still unable to speak, so this causes Bart and Lisa to enquire as to what their first words were. Through a series of flashbacks we see both Bart and Lisa's first vocal experiences until the very last scene when Homer confides in Maggie that he hopes she never says a word.
Elizabeth Taylor provided the one and only word she does say.... "daddy".
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