eager beaver

eager beaver idiom
An exceptionally zealous person, one who habitually takes on more tasks or works harder than others. For example, Bill is a real eager beaver, always volunteering to stay late. This expression became especially popular during World War II, applied to recruits anxious to impress their commanding officers by such behavior. [First half of 1900s]

The American Heritage® Dictionary of Idioms by Christine Ammer. Copyright © 2003, 1997 by The Christine Ammer 1992 Trust. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

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