User blog comment:SeddieAddiction/Favorite Line?/@comment-7814097-20110623151428

Spencer: "Why is there a mirror in here, and why can't I see out?"

Carly: "It's one way glass."

Spencer: "Then you can't see anything I'm doing!" *starts doing a weird little dance*

Carly: *slight chuckle* "No, we can see you, but you can't see us."

Spencer: *nods* "Oh, right, right."

I also like one from iBloop, but it's Miranda and Jennette -

Miranda (as Carly): "If I'm going to the dance with Gibby-"

Jennette: "You're going to te dance with Gibby? *happy jump* Alright!"