I owned a standardbred whose registered name was apparently (I didn't have his papers) Hi Big Boy. Not TOO bad, but I couldn't help but imagine it in a sultry, breathy, Marilyn Monroe voice. I called him Logan.
My friend I ride with now has a horse whose registered name is Sheza Tight Fit. Ew.
I saw one on Craigslist with an even worse name, but can't remember it now. Something along the lines of Love's Interrupted Desire or something equally Ewww.
To switch gears, I knew a gal who had a horse named Fletcher. LOVED that name.