dummy up vs be quiet

dummy up and be quiet both are verbs.

Word	Noun	Adjective	Verb	Adverb
dummy up	No	No	Yes	No
be quiet	No	No	Yes	No

As verbs, dummy up and be quiet are synonyms defined as:

Other synonyms of dummy up include belt up, button up, clam up, close up, keep mum, shut up.

dummy up (verb)	be quiet (verb)
refuse to talk or stop talking; fall silent	refuse to talk or stop talking; fall silent
make a dummy of