drop-dead vs slang

drop-dead is not a noun while slang is a noun.

Word	Noun	Adjective	Verb	Adverb
drop-dead	No	No	No	Yes
slang	Yes	No	Yes	No

drop-dead (noun)	slang (noun)
	a characteristic language of a particular group (as among thieves)
	informal language consisting of words and expressions that are not considered appropriate for formal occasions; often vituperative or vulgar

drop-dead (adverb)	slang (adverb)
stunningly or breathtakingly