Wiktionary
vb. 1 To make a mock-up or prototype version of something, without some or all off its intended functionality. 2 (context informal English) To suddenly stop talking
WordNet
Usage examples of "dummy up".
She hoisted the dummy up from the chair where it had spent the day beside Lindy's dummy.
He ordered the stenographer to transcribe the notes and have the statement typed, and told the detectives to lock Dummy up until they questioned Cassie.
The candidate was required to lift the dummy up, holding it from behind with their arms wrapped around to the front, and drag it one hundred feet without dropping the dummy.
None of the guards had seen anybody lift the dummy up the flag rope.
I thought she was snoring in her tent, and somebody had tied a stuffed dummy up there on her horse.
We moved him by night and the next morning we stuck a dummy up in the window of the jail.
We put that dummy up just before daylight and then Cap, Orrin, and me, we took to the hills right where we knew we ought to be.