fob vs pull a fast one on

fob is a noun but pull a fast one on is not a noun.

Word	Noun	Adjective	Verb	Adverb
fob	Yes	No	Yes	No
pull a fast one on	No	No	Yes	No

As verbs, fob and pull a fast one on are synonyms defined as:

Other synonyms of fob include flim-flam, fox, play a joke on, play a trick on, play tricks, trick.

fob (noun)	pull a fast one on (noun)
short chain or ribbon attaching a pocket watch to a man's vest
an adornment that hangs from a watch chain
a vest pocket to hold a pocket watch

fob (verb)	pull a fast one on (verb)
deceive somebody	deceive somebody