That 'quack' almost killed me by prescribing the wrong medication.
Her doctor turned out to be a real 'quack'.
We could hear the ducks 'quacking'.
(..) increasingly complex. Look at this, John. What? What? - Dr. Rosen said... - Rosen! That quack! "Schizophrenic break from reality," right? Psychological bullshit! Look at me, John. John, look at me. Do I look like I'm imagined? (..)2001 A Beautiful Mind