I'm looking for the title of a short story, NOT "Lamb to the Slaughter," but another one I used to compare and contrast with it. It had a wife and husband, very much in 1950s roles, talking at home, until the wife becomes more and more infuriated with what a bore he is, and begins to giggle to herself about the random thought of killing him, until finally she does.
What a Thought by Shirley Jackson.
According to Lithub:
In “What a Thought,” a housewife sits reading a boring book and fantasizes bashing in her husband’s head with a glass ashtray.
The following are a couple of excerpts directly from the short story showing the wife
(1) "gigg[ling] to herself about the random thought of killing him"
"The idea of smashing the glass ashtray over her husband's head had never before occured to Margaret, but now it would not leave her mind. She stirred uneasily in her chair, thinking: what a terrible thought to have, whatever made me think of such a thing? Probably a perverted affectionate gesture, and she laughed."
and (2) murdering her huband (appearing in the last line of the story)
"I don't want to," she said as she struck him."