I have previously posted one of my favorite ones -- Assaj Ventress, speaking to Count Dooku.
Assaj: "...I am Sith."
Dooku: (having just landed from about 50 feet up, cushioning his landing with the Force) "You are no Sith. The primary characteristic of the Sith was that they knew now fear... and I sense MUCH fear in you."
Assaj: "You are a foolish old man who knows NOTHING of the Dark Side!"
Dooku (with an amused, raised eyebrow): "Oh, REALLY." (Fries Assaj with Force Lightning)
Well, last night I found another Great Spectacularly WRONG! line. I was watching Quantum of Solace (the latest James Bond flick):
Villain: (passes around a photo)"Do you know who this is?"
(after several people take a look)
Crooked CIA Agent: "... That's James Bond. British Secret Service."
Villain: "I need you to eliminate him for me."
Crooked CIA Agent (with a confident smile): "That won't be a problem."
I almost DIED laughing at that line.