Origin of the idiom "Mind your P's and Q's"
Mind Your P's & Q's
Dear Evan: I was wondering where the expression "Mind your P's and Q's" came from -- Sarah, Natrona Heights, PA.
First of all, I must say that I really like the card Sarah used to send in her question, which features a small dog evidently named Claudia. I'm a sucker for dog pictures.
As to where "mind your P's and Q's," meaning "be very careful" or "behave yourself" came from, I'm afraid that there is no clear answer, though folks have been saying it since the late 1700's. The consolation is that there are a number of fascinating theories, so you can pretty much take your pick of the following.
One theory is that the phrase comes from the practice in certain British pubs of tallying a customer's purchases on a blackboard behind the bar, with the notation "P" standing for "pints" and "Q" for quarts. If a customer failed to pay close attention and "mind his P's and Q's," he might well find by evening's end that the barkeep had padded his tab.
Another theory, drawn from the schoolroom, is that any child approaching the mystery of penmanship soon discovers that the lowercase "p" is devilishly easy to confuse with the lowercase "q." Thus, the theory goes, generations of teachers exhorting their small charges to "mind your P's and Q's" created a enduring metaphor for being attentive and careful. A similar theory centers on typesetters in old-fashioned printing shops, where the danger of confusing lowercase "p" and "q" was increased because typesetters had to view the typeset text backwards. Still other theories tie the "P" to "pea" cloth (the rough fabric used in "pea jackets") and the "Q" to "queue," which meant a ponytail, either that of the fancy wigs worn by courtiers of the day or the real ponytails commonly worn by sailors. In the upscale version of this theory, young aristocrats were cautioned not to get the powder from their wigs on their jackets made of pea cloth. The sailor version has old salts advising newcomers to dip their ponytails in tar (a common practice, believe it or not), but to avoid soiling their pea jackets with the tar.
Bob's Your Uncle, Lame Duck, Malarkey, Dressed to the Nines, P's and Q's, and "Uxorious" -- threat or menace?
Pope of the Dictionary.com Forum