The creators seem to have mistaken the term "suckling pig" for "sucking pig". A delivery man carrying a live pig is chastised because it is "barely suckling", and responds by stuffing an apple in its mouth (a la a roast whole pig), which it immediately sucks on. However, a "suckling pig" is not one that is sucking on something, but rather a piglet young enough to still be nursing on its mother's milk, generally less than six weeks old.