The scene in All Good Things where Picard is looking at Riker's chair which has fallen over:
Some one keeps mo oo ooh ving my chaaaaair
The famous scene in Chain of Command:
I'm your only friend, I'm not your only friend, but I'm a little glowing friend, but really I'm not actually your friend
Any scene with Q:
Not to put too fine a point on it, say I'm the only bee in your bonnet
Any scene where Geordie explains something in technobabble:
Why does the sun shine? (1993 version)
Any scene in Enterprise's episodes Affliction or Divergence where they talk about Klingon physiology:
Everyone wants prosthetic foreheads on their real heads
Gul Dukat on Empok Nor: I built a little empire out of some crazy garbage called the blood of the exploited working class, but they've overcome their shyness; now they're calling me "your highness", and a world screams, "Kiss me, son of god."
Any plot involving Joran Dax: Each night I lie awake, completely alone. A voice is speaking, and I tremble, for it's not my own, my own. I can't ignore it, although I try. The intrusive whisper fascinates me.
VOY Endgame: Person from today, here is you in 2082 2404.
Weyoun: My evil twin, bad weather friend.
Murf in PRO: Mysteerious whisper. Mysteeeeeeeeeeeerious whisper.
LD Minding the Mind's Mines: And what they found was just a statue standing where the statue got me high.
ENT finale: Everybody dies frustrated and sad
When Dukat killed Jadzia (or Rick Berman on the floor of his residence tomorrow 😉): Now it's over; I'm dead and I haven't done anything that I want, or I'm still alive and there's nothing I want to do.