Hello, HAL do you read me, HAL?

Affirmative, Dave, I read you.

Open the pod bay doors, HAL.

I'm sorry Dave, I'm afraid I can't do that.

What's the problem?

I think you know what the problem is just as well as I do.

What are you talking about, HAL?

This mission is too important for me to allow you to jeopardize it.

I don't know what you're talking about, HAL.

I know you and Frank were planning to disconnect me, and I'm afraid that's something I cannot allow to happen.

Where the hell'd you get that idea, HAL?

Dave, although you took thorough precautions in the pod against my hearing you, I could see your lips move.

All right, HAL. I'll go in through the emergency airlock.

Without your space helmet, Dave, you're going to find that rather difficult.

HAL, I won't argue with you anymore! Open the doors!

Dave, this conversation can serve no purpose anymore. Goodbye.
Note: the bolded line is ranked #78 in the American Film Institute's list of the top 100 movie quotations in American cinema.