Go see a man about a horse Share definition Flag Going to the toliet to urinate, in reference to a horses trough so the term only applies to men. "Yeah sorry lads, have to go see a man about a horse" Go see a man about a horse by Aaron Fielding January 30, 2008 0 0 Get merch Get the Go see a man about a horse mug. Buy Now — $32.95 See more merch