Usage patterns
ズケズケ(と)言うto say something bluntly, without holding back
He bluntly points out other people's flaws.
〈人〉にズケズケ(と)言うto say something bluntly to someone
She spoke frankly and bluntly to her boss, giving her opinion.
ズケズケ(と)ものを言うto speak one's mind bluntly, without mincing words
My grandmother has always been someone who speaks her mind bluntly.