Bee in my bonnet

[bobsailer]

What on earth have bees got to do with spelling?

[geofbob]

The "bee" in "spelling bee" was originally an American expression for a group of people who joined together for joint instruction or amusement. It was presumably derived from the way bees work together for the good of the colony. In addition to spelling bees, there were quilting bees and [corn] husking bees.

[larabell]

That's what i've always heard, and I see how it applies to quilting bees, apple bees, etc. but I'm not sure about the spelling bees.

[Ginbottle]

To substitute B's for business, it would work in all cases. Simply means to work hard in connection to the mentioned verb.