Why "hand over fist" means "very rapidly"? Any good explanations for that?

Question

Answer

hand over fist= fast
If you make or lose money hand over fist, you make or lose a lot of money very quickly
 Example: Business was  so good  that we were making money hand over fist.

Answer

Dear sam
meaning of idiomatic phrases has no why.

Why " break a leg" means  ..... good luck

Answer

hand over fist 	
	
energetically and rapidly
He completed his assignments hand over fist.

http://www.urbandictionary.com/define.php?term=hand%20over%20fist
http://idioms.thefreedictionary.com/hand+over+fist

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