frig around vs bum

frig around is not a noun while bum is a noun.

Word	Noun	Adjective	Verb	Adverb
frig around	No	No	Yes	No
bum	Yes	Yes	Yes	No

As verbs, frig around and bum are synonyms defined as:

frig around (noun)	bum (noun)
	the fleshy part of the human body that you sit on
	a vagrant
	a person who is deemed to be despicable or contemptible
	person who does no work

frig around (adjective)	bum (adjective)
	of very poor quality; flimsy

frig around (verb)	bum (verb)
be lazy or idle	ask for and get free; be a parasite
	be lazy or idle