Princess Bride:

"You keep using that word. I do not think you know what it means."

There is no spoon. The Matrix
Go ahead make my day Dirty Harry
What does the yellow light mean TV show Jim Ignatowski (Christopher Lloyd)

What Knockers! Why thank you doctor. (Young Frankenstein, of course).

And there was much rejoicing (Monty Python and the Holy Grail) along with many others.

You're gonna need a bigger quote (sorry couldn't resist it!)

"get away from her ...you BITCH !!!" - Aliens

"Hello, my name is Inigo Montoya. You killed my father. Prepare to die" Princess Bride
"I love the smell of napalm in the morning" Apocalypse Now.

“You’re killin’ me smalls!” The Sandlot

"Some men are born mediocre, some men achieve mediocrity, and some men have mediocrity thrust upon them."

• Catch 22

Or for brevity, there's always, "Pinky, are you thinking what I'm thinking?"

From Forest Gump. . .

"and just like that (insert profound change)"

I'd tell you but I'd be breaking the first rule.

There are so many. The movie "A Few Good Men" has some really good ones.

You were sick the day they taught law at law school.

You really got to hand it to those federal marshalls, boy.

Thank you for playing should we or should we not follow the advice of the galacticly stupid.

We either get it done today or no joking Kafee, I'm going to hang you boy from a fucking yardarm.

Dave, sherbie doesn't think they hang people from yardarms anymore.

My client's a moron, that's not against the law.

And the hits just keep on coming.

And of course the most famous one:
You can't handle the truth.

Great movie.

"After fifteen minutes I wanted to marry her, and after half an hour I completely gave up the idea of stealing her purse." (Virgil Starkwell in "Take the Money and Run" )