See A Man About A Horse Edit Meaning

1.

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.

2.

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."

3.

urination by a male

See Big Steve