Dummy-up 

To make like a dummy - to SHUT UP!

"If the cops come around just dummy up."

Dummy-up by El Loudo February 10, 2005

Dummy-up 

Smarten up
Quit being an idiot

Dummy-up and get out of the car.

Dummy-up by Death February 8, 2005

dummy up

verb: to recommend to someone to keep quiet before they end up saying or doing something to prove their stupidity. The person often thinks they are undoudtedly correct. Often what they are saying refers to someone in their presence that they are unaware the story effects.

person 1: Hey, did you here that Joe got busted at Macy's ? (Joe's mom is right behind person 1 and overhears this story)

person 2 : Dude, why don't you dummy up !!

person 1 : Huh?

dummy up by ChrisL6464 April 10, 2010

dummy up

Verb: to screw over, go back on your word, mess up, act stupid, say something retarded, piss some one off, be trippin on some one or basically do anythin that could make someone mad or think your stupid
Adjective: Someone who dummies up

Verb: That bitch just dummied the fuck up.
Adjective: You are soo dummy up right now.
That dude is DUMMY UP.
You dummy up asshole.

dummy up by lil nem June 11, 2006

up the dummy 

When an inmate pulls his penis out for a female staff member.

Hey Sarge, dude on 5 galley up the dummy on the nurse again.

up the dummy by Lt Gray K3-34 May 19, 2020