per Wikipedia...
" Although Pontiac had strenuously promoted the GTO in advertising as the "GTO Tiger," it had become known in the youth market as the "Goat." Pontiac management attempted to make use of the new nickname in advertising but were vetoed by upper management, which was dismayed by its irreverent tone"
It is thought it started simply because "goat" was easier to say than the 3 sylables of G T O .
also, there was a saying to go along with the nickname: "Goats will eat anything."
goat
A Kid. A Baby Goat (as well as a Young Goat) is called a 'KID'
"Goat" is a generic term for the animal and refers to both genders. A male goat is called a "Billy Goat" and a female goat is called a "Nanny Goat". A young goat is called a "Kid".
A baby goat is called a kid.
A young goat is called a kid.
female goat is called a doe
A doe or nanny.a mature female goat is called a Nanny Goat
A young Goat is called a kid
it is called a buck A desexed male goat is called a wether
a baby goat is a 'kid'
A baby goat is the offspring of a doe and a buck goat and it is called a kid.
A uncastrated goat is called a buck.