What is the meaning of a bee in bonnet?

"A bee in one's bonnet" is an idiom in English that means to have an obsession or preoccupation with something, often to the point of eccentricity or foolishness.

It is thought to have originated in the 17th century when the term "bee" was used to describe a busy, buzzing activity. The phrase "a bee in one's bonnet" was used to describe someone who was so obsessed with a particular idea that they were acting irrationally or eccentrically, as if a bee had gotten into their bonnet and was buzzing around inside their head.

Today, the idiom is still used in the same way to describe someone who is overly focused on or preoccupied with something, often to the point of being ridiculous or impractical.