Sometimes this is confused with the old saying "I've gotta see a man about a horse." Mysterious and cheeky.
The phrase "2 men 1 horse" brings to mind a few different possibilities, but one of the most well-known references is to a somewhat infamous and humorous internet meme that originated from a supposed urban legend or joke. The concept typically involves a comedic and often nonsensical scenario. However, without further context, it's a bit tricky to create a post that accurately reflects what you're looking for. 2 men 1 horse