Miriam Jones points to a site devoted to violations by Jane Austen and other canonized authors of the rules everyone learns in English class. Or particular interest to closeted English majors is a section on the use of “they” and “their” as singular pronouns.
An example highlighted by Ms. Jones shows that even Shakespeare broke the rule:
There’s not a man I meet but doth salute me,
As if I were their well-acquainted friend.
(Comedy of Errors IV.3)
And here’s an example from the King James Bible:
Let nothing be done through strife or vainglory; but in lowliness of mind let each esteem others better than themselves. (Philippians 2:3)
Nobody tell Mr. Maud, okay? These are the kinds of things we debate, late at night, over tumblers of bourbon.*
* So what if both of the tumblers are mine?