"MACDUFF: [on hearing that his family and servants have all been killed]
"All my pretty ones?
Did you say all? O hell-kite! All?
What, all my pretty chickens and their dam
At one fell swoop?
"The kite referred to is a hunting bird, like the Red Kite, which was common in England in Tudor times and is now making a welcome return after near extinction in the 20th century. The swoop (or stoop as is now said) is the rapid descent made by the bird when capturing prey.
"Shakespeare used the imagery of a hunting bird's 'fell swoop' to indicate the ruthless and deadly attack by Macbeth's agents.
"In the intervening years we have rather lost the original meaning and use it now to convey suddenness rather than savagery."
http://www.phrases.org.uk/meanings/at-one-fell-swoop.html *********
I used "one fell swoop" in a comment just now, recalling the silly alternative. I thought some famous aphorist had coined "foop" -- but Google doesn't seem to think so. Google did list a curious blog as succeeding one called "one swell foop," so I went there:
http://www.wendell.me/ Sadly, the talented "Wendell" has folded his proverbial tent, giving up bloggery. "Even as I have ignored the fact that I was neglecting almost everything else in favor of my on-line identity, I have found it getting harder and harder to sustain it."