For instance.....The question where does the saying "The bees knees" come from was posed on this site. The answers were senseless dribble at best. The correct answer.
Ever wondered why we say this most odd expression: the bee’s knees?
It all started with another expression, still used today.
The expression ‘the be-all and [the] end-all’, meaning chiefly ‘the central or most important element’ is (like ‘one fell swoop’) a quotation from Macbeth. Macbeth is contemplating killing Duncan: “..that but this blow/Might be the be-all and the end-all…/..We’d jump [ie risk] the life to come.” (Macbeth, I.vii.4ff)
This passage is a well-known one, and the phrase the be-all and [the] end-all has been popular over the years. It is usually found without the second ‘the’.
Though many people are aware that it is a Shakespearean allusion, it is not as common as, say, ‘to be or not to be’ and it is usually used without any special reference to Shakespeare.
After years of use, ‘the be-all and [the] end-all’ became shortened to: the Bs and Es (the be-all and end-all), the Bs being the things which are all and the Es being those things which end all.
As this was said, over time (if you repeat this fast, you will see), it sounds like ‘the bee’s knees’.