Term made popular by the "Fugly Horse of The Day" blog, aslo known as "FHoTD". A play on the word "homozygous" which "refers to a horse that has two of the same dominant gene (usually a Paint Horse coat pattern)"
hideozygous means: Horse with a roman nose, short neck, straight shoulder, flat back, post legs, herring gut, sickle hock, pig eyes, parrot mouth, tiny hooves, upside-down neck, no hip, 'nest' or otherwise conformationally deficient or unattractive; used for breeding simply because the horse is a "guaranteed color producer".
"Since they're all (or damn near) being bred because they're some kind of GUARANTEED color producer, we shall now call them hideozygous."
“Yep, it's hideozygous! Straight shoulder, long as a dachshund...the hog fat condition is trying to cover a multitude of sins.”