play a trick on vs fob

play a trick on is not a noun while fob is a noun.

Word	Noun	Adjective	Verb	Adverb
play a trick on	No	No	Yes	No
fob	Yes	No	Yes	No

As verbs, play a trick on and fob are synonyms defined as:

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

play a trick on (noun)	fob (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

play a trick on (verb)	fob (verb)
deceive somebody	deceive somebody