Damar: "All this talk of gods and prophets strikes me as nothing more than superstitious and nonsense". Weyoun: "It is superstitious and nonsense". Damar: "You believe the Founders are gods, don't you"? Weyoun: "That's different"! Damar: [laugh] "In what ways"! Weyoun: "The Founders are gods"!
Worf - "Today is a good day to die, and the day is not yet over." I don't think you can get any tougher than that.
Slightly earlier, while not exactly a "line," the look Saavik gives Kirk in the lift. The way her eyes tell Kirk; "what are you waiting for, tear off my fukk clothes ... here, I'll put my hands behind my back for you." I mean really!
"Logic is a little tweeting bird, chirping in a meadow. Logic is a wreath of pretty flowers which smell bad."
Major Kira in "Emissary" "You’re probably right Jasad and if you were dealing with a Starfleet officer they would probably admit we have a hopeless cause here. But I am just a Bajoran whose been fighting a hopeless cause against the Cardassians all her life so if you want a war, I’ll give you one.’ That scene always give me chills. Captain Sisko in "A Call to Arms" "And I promise you, I will not rest, until I stand with you again - here, in this place where I belong." An awesome declaration of absolute intent and clarity on Sisko's part, that has a nice, almost poetic feel to it, especially considering Sisko's personal journey over his time in DS9, and the fact that he did not want to be there in the beginning.
There are two I can think of immediately. Both are from the TNG episode "Lower Decks": [scene in Ten Forward - Worf is speaking to Sito Jaxa, as the other officers sit at a table nearby observing] Lavelle: I wonder what he's saying to her. Taurik: Did you ever consider learning how to lip read? Lavelle: You think Worf's chewing her out? Ben: No, he always looks like that. And a few moments later... Lavelle: Riker? I bet he sleeps in his uniform. Ben: You only think that because he's your C.O. You'd really like him if you got to know him. Lavelle: Right. Taurik: He is convinced Commander Riker doesn't like him. Ben: Why? Did you crash the ship into something? It's the expression on Ben's face that really sells it.
Bashir: What I want to know is, out of all the stories you told me which ones were true and which ones weren't? Garak: My dear doctor...they're all true. Bashir: Even the lies? Garak: Especially the lies.
[Star Trek TNG: "Captain's Holiday"] [Picard is trying to relax in the sun] [A Risan named Joval picks up Horga'hn] Joval: "The Horga'hn is the Risian symbol of sexuality. To own one is to call forth its powers. To display it is to announce you are seeking jamaharon." Picard: *sigh* "Riker!" Joval: "Do you seek jamaharon?" Picard: "I don't even know what it means. The Horga'hn is for a friend." Joval: "I see. Someone close to you?" Picard: "That's right." Joval: "Someone you love?" Picard: "I wouldn't go that far." I can't hear that line without nearly peeing myself.
"Q the liar! Q the misenthrope! "Q the miserable, Q the desperate! What must I do to convince you people?!" "Die." "Oh, very clever, Worf. Eat any good books lately?"
Picard: If we're going to be damned, let's be damned for who we really are. Picard: The courtroom is a crucible. In it we burn away irrelevencies untill we are left with a pure product -the truth, for all time. Odo: With all this lip smacking, who can hear anything? And many more.