<P> Another proposal concerns the use of Norman French in medieval England; as the English dialect of the 11th century had no qs, one must watch their usage in court or discourse with the French Norman conquerors . </P> <P> Quinion cites an apparently related expression of pee and kew for "highest quality" used in 17th - century English . </P>

Where did the expression watch your p's and q's come from