Major Bloodnok: "He may be a king's messenger. Let him in, but first, make him give the password, which is 'I don't know'."
Eccles: "Okay. 'I don't know'. That'll fox him. (Reaches the door). Erm, hello, my good man. Now then, what's the password?"
Seagoon: "I don't know."
Eccles: "Oh, he got it right first time.."
— The Goon Show: "The Rent Collectors"
Glados: All right, paradox time. This...sentence...is...FALSE! Don'tthinkaboutit, don'tthinkaboutit...(Frankenturrets start shorting out and exploding)
Wheatley: Um..."True". I'll go "True". Neh, that was easy. I'll be honest, I might have heard that one before though. Sort of cheating.
Glados: It's a paradox! There IS no answer! Look! This place is gonna blow up if I don't get back in my body!
Wheatley: Uuh, "False". I'll go "False".
When you talk, sometimes I get confused. My ideas of what's right and wrong get mixed up. That's why I'm bringing this. As soon as I start thinking it's all right to steal from our employees, I'm going to start hitting you with the stick.
— Helix, Freefall
It's like, even when we win, he wins.
The little guy did something to your heads. I gave him the explodo because I am clever.
"One second he's dumb as an ox and the next he's sharp as a whip...that's why I hate him so much."
— Izaya Orihara stating his opinion of Shizuo.
"Amazing. He'd actually have to be smarter to do something stupid"