When Batman finds Harley Quinn and the Joker, the latter makes a warm greeting, and they both act as if they were on a TV sitcom. Hilarity Ensues. Until Tim shows up, of course...
When talking about starting a family, we get this from Mr. and Mrs. J.
Joker: And Harley and I have been thinking that it's time to start a family. Add a Joker Jr. to our merry brood! Harley: (looking disgusted) But rather than go through the joy of childbirth, we decided to adopt!
Given that the following line is spoken by the Joker, it doesn't surprise that it manages to be both a CMOF and terrifying:
Joker: It would be funny if it wasn't so pathetic.(Beat) Oh, what the heck, I'll laugh anyway! (Evil Laugh)
Makes it even more sweeter when in the future Terry, albeit unknowingly, says a rephrase of the line when fighting Joker.
Terry: You make me laugh, but only because I think you're kind of pathetic. (laughs mockingly)