it is also an expression....my grandma used to say "fiddlesticks" when she was disappointed,

The expression 'Fiddlesticks' is common enough, certainly more widespread than the obscure musical folklore under discussion here. Simply put a Fiddlestick is a violin bow (for which many classical players today use the term 'stick' - folk players too??). That 'beating sticks / straws' is now called 'fiddle sticks' is by way of folksy revival usage, pure and simple, whereas the term 'Fiddlesticks' goes back to Shakespeare's time, and it's common usage throughout the English speaking world reflects this. For more on Fiddlesticks as a term:

http://www.worldwidewords.org/qa/qa-fid1.htm

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Otherwise, 'beating the sticks' has echoes of the Gyimes fiddle & gardon music in that the husband plays the clever stuff whilst the wife knocks out a rhythmic drone by way of accompanyment. Obviously with 'beating the sticks' all you need is a couple of knitting needles rather than the unweildy & grotesque utogardon, which approximates the look of a more sophisticated instrument by way of folk-art. I dare say these days you can buy pro-quality utogardons made by skilled luthiers!

http://www.youtube.com/watch?v=zOK9QAvQHmo (the gardon doesn't come in until 7.45, but it's worth watching it all...)