I'm not going to pick a favourite, but I'll throw some favourites out there.
Blake's 7, 'Orbit', where Avon, Vila, and ORAC are in a shuttle that's seventy kilos too heavy to escape a gravity well:
Avon: Not enough! Not nearly enough! Damn it, what weighs seventy kilos?
ORAC: Vila weighs seventy-three kilos, Avon.
Firefly, 'Serenity, Part II', where Dobson has a gun to River's head, using her as a human shield:
Dobson: I'm not playing anymore.
Mal walks up the ramp.
Dobson: Anybody makes so much as a...
Stargate SG-1, '1969', where SG-1 appeared inside a secure US military facility in 1969:
US Soldier: [Something in Russian]
Daniel: Nyet.
Jack: Daniel?
Daniel: He just asked if we were Soviet spies. I just… oh.
Star Trek, The Next Generation, 'All Good Things, Part II', where the Pasteur is under heavy attack from Klingon ships. And then the Enterprise-D-of-the-future decloaks, with some godawful-normous underslung phaser cannon...
Admiral Riker: I had a feeling you weren't going to listen to me. Stand by whileI try to get the Klingons' attention...
-Hyp.