pig it vs pig

pig it is not a noun while pig is a noun.

Word	Noun	Adjective	Verb	Adverb
pig it	No	No	Yes	No
pig	Yes	No	Yes	No

As verbs, pig it and pig are synonyms defined as:

pig it (noun)	pig (noun)
	domestic swine
	a crude block of metal (lead or iron) poured from a smelting furnace
	mold consisting of a bed of sand in which pig iron is cast
	a person regarded as greedy and pig-like
	uncomplimentary terms for a policeman
	a coarse obnoxious person