Too Clever by Half

origin three shakes of a lambs tail

Literally that. Three shakes of a lamb's tail can happen very quickly, hence the analogy. Quite a common phrase in the UK. Must be 100s of years old and based on simple observation. Used to describe something happening quickly, usually the time elapsing before a task is completed.

The U.S. version is "two shakes of a lamb's tail." Why the difference? Unless we have slower lambs over here, you can blame exchange rates. ~rb

My knowledge of Econ is deep,
The rate that you quote is too steep.
The dollar, I've found
Is two to the pound.
Not 3-to-2 shakes, as in sheep.

These ratios of shillings to dimes,
Historically, change with the times.
So my math's obsolete?
I, reduced to a bleat,
Maintain it's the least of all crimes. ~rb

The rates fluctuate, what to do?
Hindsight will tell us what's true.
We just can't know nuttin'
Til lamb turns to mutton,
The fault is the clock, and not ewe.