“Didn’t we have some fun though? Remember when the platform was sliding into the fire pit and I said ‘Goodbye’ and you were like ‘NO WAY!’ and then I was all ‘We pretended we were going to murder you’? That was great." Probably the best quote in the game.
"Please place the Weighted Storage Cube on the Fifteen Hundred Megawatt Aperture Science Heavy Duty Super-Colliding Super Button."
"Please be advised that a noticeable taste of blood is not part of any test protocol, but is an unintended side effect of the Aperture Science Material Emancipation Grill, which may, in semi-rare cases, emancipate dental fillings, crowns, tooth enamel, and teeth."
"Please note that we have added a consequence for failure. Any contact with the chamber floor will result in an 'unsatisfactory' mark on your official testing record followed by death. Good luck!"
"If you become light headed from thirst, feel free to pass out. An intubation associate will be dispatched to revive you with peptic salve and adrenaline."
"Did you know you can donate one or all of your vital organs to the Aperture Science self esteem fund for girls? It's true!"
"Although the euthanizing process is remarkably painful, eight out of ten Aperture Science engineers believe that the companion cube is most likely incapable of feeling much pain."
"What are you doing? Stop it! I-i-i-i-i-... Weeee are pleased that you made it through the final challenge where we pretended we were going to murder you. We are very very happy for your success. We are throwing a party in honor of your tremendous success. Place the device on the ground, then lie on your stomach with your arms at your sides. A party associate will arrive shortly to collect you for your party. Make no further attempt to leave the testing area. Assume the 'Party Escort Submission Position' or you will miss the party."
"Well, you found me. Congratulations. Was it worth it? Because despite your violent behavior, the only thing you've managed to break so far is my heart. Maybe you could settle for that and we'll just call it a day. I guess we both know that isn't going to happen. You chose this path. Now I have a surprise for you. Deploying surprise in five, four... (Morality core falls off GLaDOS) Time out for a second. That wasn't supposed to happen. Do you see that thing that fell out of me? What is that? It's not the surprise. I've never seen it before. Never mind. It's a mystery I'll solve later... by myself... because you'll be dead."
(Probably my favorite line... err... lines... in the game.)
"I'd just like to point out that you were given every opportunity to succeed. There was even going to be a party for you. A big party that all your friends were invited to. I invited your best friend the companion cube. Of course, he couldn't come because you murdered him. All your other friends couldn't come either because you don't have any other friends. Because of how unlikable you are. It says so here in your personnel file: Unlikable. Liked by no one. A bitter, unlikable loner whose passing shall not be mourned. 'Shall not be mourned.' That's exactly what it says. Very formal. Very official. It also says you were adopted. So that's funny, too."
And of course, "The Enrichment Center reminds you that the Weighted Companion Cube will never threaten to stab you and, in fact, cannot speak."