play tricks vs fob

play tricks is not a noun while fob is a noun.

Word	Noun	Adjective	Verb	Adverb
play tricks	No	No	Yes	No
fob	Yes	No	Yes	No

As verbs, play tricks and fob are synonyms defined as:

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

play tricks (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 tricks (verb)	fob (verb)
deceive somebody	deceive somebody