a bee in bonnet

a bee in (one's) bonnet

An obsession, often with something that is strange or a source of agitation. Ever since the blizzard last year, Dad has had a bee in his bonnet about moving to a warmer climate. It seems that Mike still has a bee in his bonnet over the criticism he got in the staff meeting.
See also: bee, bonnet
Farlex Dictionary of Idioms.

a bee in (one's) bonnet

1. An impulse to do something; a notion.
2. An obsession.
See also: bee, bonnet
American Heritage® Dictionary of the English Language, Fifth Edition.
See also:
  • bee in bonnet
  • bee in one's bonnet
  • bonnet
  • a bee in (one's) bonnet
  • have a bee in (one's) bonnet
  • have a bee in your bonnet
  • get worked up about (something)
  • get worked up over (something)
  • be (as) busy as a bee
  • busy as a bee