She 'played/acted dumb' [=pretended to know or understand less than she really did] so we would assign her the easier tasks.
She thinks television is contributing to the 'dumbing down' of America.
Cutting training programs will 'dumb down' the American workforce.
(..) Where does he find these guys? Open the champagne. - And can we get some girls in here? - Careful what you wish for. - Cat got your tongue? - You dumb bitch. Nobody ever accused me of being dumb. You're dumb... for comin' here tonight. I want what you owe me. (..)2012 The Dark Knight Rises
(..) He's drawing the cops off Bane. Please! Just let me go! Please! How could you lose 'im? What, and you don't?! Then he's as dumb as he dresses. Close it off, gentlemen. Like a rat in a trap, gentlemen. You might have the wrong animal there, sir. You sure it was 'im? (..)2012 The Dark Knight Rises