why do we say eager beaver?

[r.flavell]

why do we say eager beaver?

[dilbert]

Have you ever seen a beaver?

They make me pretty eager I can tell you!

[Clanad]

Though its reputation has been questioned in recent years, the beaver has long been noted for its persistent industry. This reputation gave us the simile, "to work like a beaver," some two hundred years ago. Industrious persons have long been likened to the beaver. We English-speaking peoples are gluttons for rhymes, such as hodge-podge, helter-skelter. Therefore, within the past few years, some bright spirit did the best he could to refer to someone who was particularly avid as an "eager beaver." ...(With thanks to Wikipedia)

[Grunty]

At the age of about three, I recited this at a party, to my mother's embarrassment:

Eager Beaver, chimney sweeper

Had a wife but couldn't keep her

Had another, didn't love her

Up the chimney he did shove her

[Clare A]

Oh, Grunty - how naughty of you! When you think what is routinely yelled across the street now, it seems pretty innocent though, doesn't it?

I can remember my friend's younger brother earning a slap from their Mum for 'Flippins in the Bible/Flippins in the Book/And if you don't believe me/Then have a flippin look!'. And the word he used really was 'flippin'! 

To return to beavers, I'm with Clanad. We talk of 'beavering away' at some task, don't we?