can of worms vs colloquialism

can of worms and colloquialism both are nouns.

Word	Noun	Adjective	Verb	Adverb
can of worms	Yes	No	No	No
colloquialism	Yes	No	No	No

can of worms (noun)	colloquialism (noun)
a source of unpredictable trouble and complexity	a colloquial expression; characteristic of spoken or written communication that seeks to imitate informal speech