On Wed, 22 Sep 2010, Rich Alderson wrote:
  The practice far predates modern cooking regimina[1],
and originally
 referred to the consumption of the eggs of wild birds.  These are an
 excellent source of protein, as well as vitamin D, and easily eaten even
 by elders who have lost their teeth to the ravages of time (thus,
 "grandmother" in the saying in question).  Since they are internally
 fragile, it is simpler to suck out the contents rather than opening the
 shell more completely.
 [1] Plural of "regimen". 
Thank you
I'd bet that you habitually turn screws back to find the start of the
threads.
--
Grumpy Ol' Fred                     cisin at 
xenosoft.com