nasty vs sex activity

nasty is not a noun while sex activity is a noun.

Word	Noun	Adjective	Verb	Adverb
nasty	No	Yes	No	No
sex activity	Yes	No	No	No

nasty (noun)	sex activity (noun)
	activities associated with sexual intercourse

nasty (adjective)	sex activity (adjective)
offensive or even (of persons) malicious
exasperatingly difficult to handle or circumvent
disgustingly dirty; filled or smeared with offensive matter
characterized by obscenity