bee in one's bonnet

Cultural  

1. A chronic preoccupation, often fanciful or eccentric: “My cousin has a bee in his bonnet about the rudeness of local cabdrivers; he's written four letters to the editor on the subject.”

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bee in one's bonnet Idioms  

1. A strange idea or notion; also, an idea that is harped on, an obsession. For example, Bill's got a bee in his bonnet about burglars; he's always imagining strange noises. This term, which replaced the earlier have bees in one's head, transfers the buzzing of a bee inside one's hat to a weird idea in one's head. [Second half of 1600s]

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Example Sentences

Bees′winged, so old as to show beeswing.—A bee in one's bonnet, a whimsical or crazy fancy on some point.

From Chambers's Twentieth Century Dictionary (part 1 of 4: A-D) by Various