The square root of rope is string.

All right, I've been thinking, when life gives you lemons, don't make lemonade! Make life take the lemons back! Get Mad! I don't want your damn lemons! What am I supposed to do with these? Demand to see life's manager! Make life rue the day it thought it could give Cave Johnson lemons! Do you know who I am? I'm the man whose gonna burn your house down - with the lemons! I'm gonna get my engineers to invent a combustible lemon that'll burn your house down!

It's not out of the question that you might have a very minor case of serious brain damage.

Those of you who volunteered to be injected with praying mantis DNA, I've got some good news and some bad news. Bad news is we're postponing those tests indefinitely. Good news is we've got a much better test for you: fighting an army of mantis men. Pick up a rifle and follow the yellow line. You'll know when the test starts.

GLaDOS: Oh, thank God you're all right. You know, being Caroline taught me a valuable lesson. I thought you were my greatest enemy, when all along you were my best friend. The surge of emotion that shot through me when I saved your life taught me an even more valuable lesson - where Caroline lives in my brain.

beep

Announcer: Caroline deleted.

GLaDOS: Goodbye, Caroline. You know, deleting Caroline just now taught me a valuable lesson: the best solution to a problem is usually the easiest one. And I'll be honest. Killing you? Is hard. You know what my days used to be like? I just tested. Nobody murdered me. Or put me in a potato. Or fed me to birds. I had a pretty good life. And then you showed up. You dangerous, mute lunatic. So you know what? You win. Just go.

GLaDOS starts Chell's elevator moving up; she laughs softly

GLaDOS: It's been fun. Don't come back.