see a man about a dog
Definition from Wiktionary, the free dictionary
From the 1866 Dion Boucicault play, Flying Scud, in which a character knowingly breezes past a difficult situation saying, "Excuse me Mr. Quail, I can't stop; I've got to see a man about a dog."
- (idiomatic) Used as an excuse for leaving without giving the real reason (especially if the reason is to go to the toilet, or to have a drink).
- The most common variation is to "see a man about a horse".
- Almost any noun can be substituted as a way of giving the hearer a hint about one's purpose in departing.
- The inversion to "see a dog about a man" eliminates any lingering uncertainty about whether the hearer is being put off.
- A shorter variant is to "see a man".