Verb
see a man about a horse (third-person singular simple present sees a man about a horse, present participle seeing a man about a horse, simple past saw a man about a horse, past participle seen a man about a horse)
(idiomatic, euphemistic) Used in place of a real explanation when excusing oneself for a short period of time, particularly to use a toilet.
I'll be back in two shakes of a lamb's tail. I've just got to visit the ladies' room to see a man about a horse.