When Lex Luthor is about to announce the new member of the LOD, Ivy tries to distract Harley by offering to form a group together. She said, "It'll be like 'Harley & Ivy,'" which is episode 47 of season 1 of Batman: The Animated Series (1992).
This episode features an appearance by Aquaman in a highly different characterization to the Jason Momoa movies. This was a deliberate ploy on the part of showrunner, Justin Halpern.
The L.O.D. of the title refers to the Legion of Doom.