The public hearing scene in Star Trek IV: The Voyage Home

Sarek and the Klingon ambassador are engaged in some pretty nifty verbal sparring. Sarek's "... do you de-ny these events" is answered with "we de-ny nothing" with the just the right amount of mockery (the Klingon ambassador mimics the cadence and tonal dynamics on the word "deny" [what a catty fellow!]) but the best part is when the Klingon ambassador leaves in a huff, and there's a voice that barely arises above the chatter from the gallery and yells, "You pompous ass!" That's the moment that Star Trek IV transcends the franchise and its genre to become a neo-realist masterpiece! (Some might argue that that moment comes later, when Spock nerve-pinches the SF boombox punk on the bus, but they're wrong!)