A person conceived via anal sex as opposed to vaginal sex that is as a result hideously disfigured to the point of heinousness.
Phil is a buttbaby and he therefore is fucked up looking.
A ButtBabyy is any child that results from semen seeping into the vagina after anal sex. ButtBaby's can be prevented by using a condom, birth control pills, other contraceptives, and by simply not engaging in anal sex.
Father:"Son, now that your 16, its time we tell you that you werent planned, you were a ButtBaby."
Son:"Thats okay, becuase my girlfreind is pregnent with a ButtBaby."