Please forgive me for asking a language question here, but it keeps haunting me:
Where does the phrase: 'to mind one's Ps and Qs' come from? I know what that means (or so I think) but am puzzled about its origin. Can anybody help?
I've been getting up the courage to ask this question for a long time, but I've no idea how to keep it travel-related! Hope I won't be found out by the moderators and terminated!