swallow the dictionary
To have and utilize a very extensive vocabulary; to use a variety of long, complicated, or uncommon words in one's speech. She must have swallowed a dictionary, because it was very hard to follow along with all the big words she was throwing around. Why do you always have to talk to use like you swallowed a dictionary?
swallow the dictionary
tv. to acquire an enormous vocabulary. (Usually in the past tense.) My uncle says I’ve swallowed the dictionary. That’s because I know so many big words.