And…one a little less well known, I’m sure:

“Farewell, T1-N1. Please do not abuse my trust and fire on the personnel while I am occupied, thereby creating a diversion that allows me to escape with the stolen files” — B4-D4, KOTOR 2

Protocol Droids + Astromech Droids = Funniest part of Star Wars! 8~D

Warcraft 2: “Yes, sir?” and “We are under attack!”

I usually say that, respectively, when my boss call me and when and perceive that a invasion in one of my servers is occurring.

“It’s time to kick ass and chew bubble gum…except I’m all out of gum!”
- Duke Nukem

“I’m gonna rip your head off and shit down your throat!”
-Duke Nukem

Defender:
Those little red guys who always chase you to your death:

bloop bloop bloop

My second favorite would be the sound of Q*bert after he jumps off the puzzle to his death:

Rwerrrrrrpt (followed by a big knock on wood thump)

Least favorite quote:

Those electric things in Tempest 2000 (that’s right, on the Atari Jaguar):

Roooarrrrr

“Have fun storming the castle!”

“What can we and I do you for?”

- Sulik, Fallout 2

GM: “So, the mage whips out a 25 foot long python.”
URIEL: “Holy crap!”
MISHA: “Excuse me!”
AIDEN: “It’s the staff, it can turn into a snake!”
URIEL: “Thank god you clarified that.”
MISHA: “Mine’s still bigger.