button up vs dummy up

button up and dummy up both are verbs.

Word	Noun	Adjective	Verb	Adverb
button up	No	No	Yes	No
dummy up	No	No	Yes	No

As verbs, button up and dummy up are synonyms defined as:

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

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