When she asks, "Do you hear yourself speak?" it's with almost morbid curiosity and before anything in her kicks in to prevent it from coming out of her mouth -

and in for a penny, in for a royal, so she sails past common sense and docks at 'doing an impression of him grandly waving his big dumb hand about like he's so superior to everything silly and mortal'. (There is no good reason why Thranduil has not yet had his obnoxiously large and unnecessarily aristocratic mannerisms lampooned by the smallest and least credible impersonator, it's probably only a matter of time.)

"Oh, those humans. At it again. I can draft the entirety of any interview I might conduct with you off that all by myself, you sound like a twat."

By the time she's got to actually calling him a twat to his face, she sounds much less hostile than when they began speaking.