I`ve always heard "Mind your P`s and Q`s!", but no one can ever tell me what it means. Can anyone here give me a real explanation on what P`s and Q`s are?

It's a term used in Pubs. P's and Q's refers to Pints and Quarts. If a customer were to get lets say, overly enthusiastic in his behavior at the bar, the bartender might say, "Mind your P's and Q's."

It most probably comes from the printing trade, where in the past small lead letters were mounted back to front in a printing frame. Because of the similarity between the letters p and the q, the apprentices were always told to beware of (or mind) their "p's and q's".

According to the Oxford English Dictionary it probably referred to children learning to write or to apprentice printers...as Fourbrick says.
There are other explanations that have been offered, such as the advice to drinkers one, also already mentioned.
Another is that it was an instruction from 18th century French dancing-teachers for gentlemen to mind their 'pieds et queues'. That's French for 'feet' and 'pigtails' (the latter being worn by men as part of their wigs in those days). Obviously, they had to be careful what happened to both, if the ladies were not to be inconvenienced!
Yet another is that it was advice to children who were going to visit relatives etc. They had to mind their ‘pleases' and ‘thankyous'!
But my advice is to stick with the kids writing or the printer's apprentices, as the OED says.

quote:

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Originally posted by deeptread:
It's a term used in Pubs. P's and Q's refers to Pints and Quarts. If a customer were to get lets say, overly enthusiastic in his behavior at the bar, the bartender might say, "Mind your P's and Q's."

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I agree. That is the only explanation I have ever heard.

Here is what the centenary edition
of Brewer's Dictionary of Phrase and
Fable says about just that:

Be very circumspect in your behaviour.
Most probably it derives from an
admonition to children learning the
alphabet to be careful to distinguish
between the forms of p and q
or to printers' apprentices in handling
and sorting type. More fancifully it is
suggested that in public houses accounts
were scored up for beer "P" for pints
and "Q" for quarts, and a customer needed
to "mind his P's and Q's" when the reckoning
came. Another is that in the France
of Louis XIV, when huge wigs were
fashionable, dancing masters would warn
their pupils to "Mind your P's (i.e.
pieds, feet) and Q's (i.e. queues, wigs)"
lest the latter fall off when bending
low to make a formal bow.

Howdy folks!
I posted a reply earlier today that included a link to uselessknowledge.com. When I finished the post, and clicked on the link, my virus software informed me that there was an infected file associated with the "pop up" ads that come up with the site. Just wanted to let everyone know about it, and sorry if it caused any problems.

p.s. KK has since removed the offending post