Which cartoon? I've seen every episode of Batman the Animated Series from the 90's and don't remember that about Harley and Ivy.

With the Robin thing, I will take your word on it. I never read much in the way of comics. My Batman knowledge comes from Batman the Animated series, the now 6 Batman movies that were made since I've been born and Batman Mask of the Phantasm which is based off the Animated Series.

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"BOY: On a hot summer night, would you offer your throat to the wolf with the red roses? GIRL: Will he offer me his mouth? BOY: Yes. GIRL: Will he offer me his teeth? BOY: Yes. GIRL: Will he offer me his jaws? BOY: Yes. GIRL: Will he offer me his hunger? BOY: Yes. GIRL: Again, will he offer me his hunger? BOY: Yes! GIRL: Yes. BOY: On a hot summer night, would you offer your throat to the wolf with the red roses? GIRL: Yes. BOY: I bet you say that to all the boys!" -Meatloaf