See a man about a horse 

It means to politely excuse yourself from a situation to go to the restroom or buy a drink. It originated from men disappearing to go bet on horse or dog races. See a man about a dog means the same thing.

The earliest confirmed publication is 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." In a listing for a 1939 revival on the NBC Radio program America's Lost Plays, Time magazine observed that the phrase is the play's "claim to fame".

During Prohibition in the United States, the phrase see a man about a horse was most commonly used in relation to the consumption or purchase of alcoholic beverages.

See a man about a horse by Coweyes February 21, 2013

See a man about a dog 

Phrase used to conceal one's true destination, especially in response to an awkward question. Is commonly used in Britain when one is headed to the toilet. See also going to see a man about a dog

"Are you and your wife coming out tonight?" "Uhhhh, I need to see a man about a dog."

"How come you're leaving the table?" "I need to see a man about a dog."

See a man about a dog by Alexandra July 29, 2004

see a man about a horse 

Any general business that needs attending to that you may not care to discuss whith the present party.

We can meet for lunch on Tuesday, since I'll be in the area; I have to see an man about a horse.

see a man about a horse by moth17 July 19, 2005

See a man about a dog 

A clever way to tell someone "non of your business".

Q. - Where are you going?
A. - To see a man about a dog.

See a man about a dog by Ms.Moe October 6, 2009

see a man about a wallaby 

go to the bathroom.

While it may be used in "Finding Nemo", Mr. Disney (who was deceased, by the way, when "Finding Nemo" was made) did not come up with it. It is an Austrailian saying which was popularized in the movie "Crocodile Dundee".

"Man, that was a great chili dog, but now I've gotta see a man about a wallaby."

see a man about a wallaby by ixolib December 10, 2008

see a man about a wallaby 

Take a crap, drop a bomb, drop some friends off at the pool, feed the porcalin, brown the water, kill a potatoe, make a deposit, feed the chickens, chop the firewood, weed the lawn, attack the castle, make an appeal, go windsurfing, see a movie, write an english paper, farfegnuegin, or make some chocolate. If you are confused, we're talking about pooping here.
The wallaby one is honestly from a Disney movie, "Finding Nemo". Man, Disney, good call!

Excuse me, I have to go see a man about a walaby. Keep rinsing, we'll start on the back molars in just a few.

see a man about a wallaby by stevie September 15, 2003

see a man about a horse 

A discreet way to leave the table at a restaurant to go to the restroom; derived from a 1940's black-and-white film (sorry, cannot recall the name) where an actor literally says it as he leaves a table to see a man at another table about a horse.

"Excuse me, I have to see a man about a horse."

see a man about a horse by James Pettit August 29, 2005