1. Refuse to talk or stop talking; fall silent
   "The suspect dummied up when questioned by the police";
   - close up, clam up [informal], shut up, belt up [Brit, informal], button up, be quiet, keep mum [informal]
    
2. Make a mock-up or prototype version of something
   "dummy up the books that are to be published";
   - dummy

Derived forms: dummies up, dummied up, dummying up

Type of: create, forbear, make, produce, refrain