human head vs mug

human head and mug both are nouns.

Word	Noun	Adjective	Verb	Adverb
human head	Yes	No	No	No
mug	Yes	No	Yes	No

human head (noun)	mug (noun)
the head of a human being	with handle and usually cylindrical
	the human face (`kisser' and `smiler' and `mug' are informal terms for `face' and `phiz' is British)
	a person who is gullible and easy to take advantage of
	the quantity that can be held in a mug

human head (verb)	mug (verb)
	To stare awkwardly
	rob at gunpoint or with the threat of violence