Christmas With the Joker - S1-E38
Joker: Jingle bells, Batman smells. Robin laid an egg. The Batmobile lost a wheel and the Joker got awaaaaaaaaayyyyy.
Rupert Thorne: All men have something to hide. The brighter the picture, the darker the negative.
Bruce Wayne: What IS this?
Salvo Smith: If it's moving, it's a rat. If it isn't, it's a cooked rat. (00:06:00)
Christmas With the Joker - S1-E38
Robin: OK, I'll make a deal with you. If we go out on patrol, and Gotham is quiet, with no sign of the Joker, we come back here, have Christmas dinner, and watch It's A Wonderful Life.
Batman: You know, I've never seen that. I could never get past the title. (00:02:20)
Answer: She escaped off-screen and created a copy of herself to fool everyone.