There's no sex scene. It's alluded to and there's some innuendo -- part of it was seen in a trailer or clip of Harley telling Nightwing to be good and he might get a cookie. Long description if you want. I suppose I don't have to use spoiler tags but whatever: Spoiler The full context is he gets tasked with finding her, they get into a fight, she pricks him with low level Joker toxin and knocks him out. He wakes up, costume still on, tied to her bed. She's discussing aloud with herself what to do with him, because she's been laying low, not communicating with her parole officer, and living in a condemned apartment building. She takes off her Superbabes uniform to change into an official Harley costume so you do see her in her stock white underwear for bit. Then in role reversal of sorts she starts to imply sex and Nightwing gets nervous then she tells him basically, I have something you want, you want something I want' then the cookie line. Then it I think it cuts to Batman doing his part of the investigation elsewhere in the city. He realizes NW hasn't checked in. Cut to him in the hall outside Harley's apartment. He hears what sounds like NW is being tortured, he's about to kick the door in, then the sounds sort of sound sexual. He opens the door. Harley and Nightwing are fully costumed having a tickle fight on the bed. Then a whole thing about Batman getting her to help stop Ivy and Floronic Man. Then Batman gives him the silent treatment. NW retorts with something like a 'like you never fooled around with a super villain before'. During the Batmobile ride, Harley basically gets annoyed with NW and tells him off that something like 'she used him for 20 minutes and she ever gets the urge again she'll get batteries.' In my opinion, it was a part of farcical nature of the movie. The Superbabes serves to show how women in the genre are objectified then Harley turns the tables on Nightwing and objectifies him, then figuratively throws him away during the Batmobile drive. It never went as far as the Deadshot/Harley scene in Assault on Arkham for example.