Addressed to the firm/unknown mug thief:
“You were clever enough to leave my mug out in the kitchen unbeknownst to me and then retrieve it back to the hideout just before I learned of its whereabouts. You win. You are one step ahead of me. Now, please return it. I am no match for you.
My mug is white, has my last name on it and was a recent family gift.”
Naturally, one cannot sit idly by while such mug thievery occurs in broad daylight IN ONE'S WORKPLACE! As a Good Samaritan, I have done my part to help curb these kinds of atrocities through poster below, which I've put up around the office.
Note: Names and identifying traits have been changed to protect the Mug-less.
UPDATE (10/25/07): The mug has been found and returned to its rightful owner.