In reference to good old Webster 1913's
definition first as a noun: 1. A tail-like appendage of hair; a pigtail.
and as a transitive verb: To fasten, as hair, in a queue.
And also in reference to Mind your Ps and Qs, a delightful write-up by Buttermaker, who unfortunately has not been seen in these parts since 2006. The write-up is an exploration of the possible origins of that phrase. One suggestion posits that at one time sailors would
pull their hair into a queue and dip it in tar, but Buttermaker could not imagine a reason for this behavior. In fact, this was a common practice, especially among marines and sailors aboard ships that were likely to be involved in combat. First, the tarred queue (and that is the origin of the slang term "tar" for sailors) kept hair maintenance to a minimum and kept it from becoming a dangerous encumbrance when climbing rigging and dealing with loose
sheets and halyards. Second, and probably more important, the tar in the queue made it into a very stiff, resilient protection for the back of the neck in hand-to-hand combat, which was very close and deadly in sea battles among the sailing vessels and galleys of the period.