For Science. You Monster.

"Are you kidding me? Did you just stuff that Aperture Science Thing-We-Don't-Know-What-It-Does into an Aperture Science Emergency Intelligence Incinerator? That has got to be the dumbest thing that-whoa, whoa, whoa... Good news. I figured what that thing you just incinerated did. It was a morality core they installed after I flooded the Enrichment Center with a deadly neurotoxin, to make me stop flooding the Enrichment Center with a deadly neurotoxin. So get comfortable while I warm up the neurotoxin emitters." -GLaDOS

"Maybe you should marry that thing since you like it so much. Do you want to marry it? WELL I WON'T LET YOU! How does that feel?" -GLaDOS 

"There was even going to be a party for you. A big party that all your friends were invited to. I even 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." -GLaDOS

"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." -GLaDOS

"When I said "deadly neurotoxin," the "deadly" was in massive sarcasm quotes. I could take a bath in this stuff. Put in on cereal, rub it right into my eyes. Honestly, it's not deadly at all... to *me*. You, on the other hand, are going to find its deadliness... a lot less funny." -GLaDOS 

"Your entire life has been a mathematical error... a mathematical error I'm about to correct!" -GLaDOS

"You think you're doing some damage? Two plus two is... Ten. IN BASE FOUR! I'M FINE!" -GLaDOS

"Have I lied to you? ... I mean, in this room?" -GLaDOS