This refers to a broad category of mentally
or physically deformed individuals. Unfortunately for these
people, they were conceived
after semen seeped from their respective
mother's anuses into their
vaginas after anal sex. This mixture of fecal
matter and sperm, that fertilized their
mother's eggs, often produced ghoulish offspring that are genetically predisposed to being very unattractive or educationally inept.
One could say that they passed a short
bus full of butt-babies on their home from
work or that they saw the maturing process of a butt-baby by watching
"Texas Chainsaw Massacre: The Beginning".