I have been reading this the last week or so and still no one has posted anything from a Dirty Harry movie; so I will.
This is my favorite one because of how he acts in the scene and how the whole thing plays out.
From Sudden Impact:
Crook: [during a diner robbery] What's you doing, you pighead sucka?
Harry Callahan: Every day for the past ten years, Loretta here's been giving me a large black coffee- except today she gives me a large black coffee and it has sugar in it. Alotta sugar. I just came back to complain.
Crook: Say what, sucka?
Harry Callahan: Well, we're not just gonna let you walk out of here.
Crook: Who'se we sucka?
Harry Callahan: [slowly drawing his .44 Magnum] Smith and Wesson... and me