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

a bee in (one's) bonnet

1. An impulse to do something; a notion.
2. An obsession.
See also: bee, bonnet