Oh I completely agree that Luna wouldn't have done the wet clothes pick-up line and I like what you did with this story, but it occurred to me (some hours after my original comment) that the best way of handling Luna would have been that she would miss the "subtly" of the comments.
Keeping in mind that writing fiction, particularly dialog, was never my strong point (a textual analysis of themes of redemption, love or religion in the series I'm your man, but that is neither here nor there at the moment), I would have handled it something like:
As Harry was studying the label of his sixth bottle of Ogden’s finest a dreamy voice pulled him out of his thoughts, “Hello Harry.”
“Did she ask you to come here Luna?” asked Harry while looking Luna up and down.
“No, I heard what happened and felt you might need a friend.”
“What I need right now is to play lion keeper.”
Luna quirked her eyebrows questioningly, “Lion keeper?” she asked.
“Yeah, you sit on your hands and knees while I feed you my meat.”
“That sounds like a fun game, but I am full right now. I just came from dinner in the Great Hall. I think the elves are celebrating also, they made the most delicious meal, though I couldn’t figure out what the cream sauce was made from.”
[From here the conversation would devolve with Harry’s comments getting more and more crude. I think at some point Harry would have to make some comment about his meat wand and Luna would respond about how it probably wouldn’t work for her because, as Ollivander always says it’s the wand that chooses the wizard or witch.]
Exasperated, Harry finally realized that Luna was not going to be chased off. Deciding to be as polite as possible Harry looks Luna in the eye and says, “You know, I really am not in the mood to be around anyone right yet.”
Luna smiles softly and returns Harry’s look while she stands up to leave, “Oh, Ok Harry, but if you ever feel like having someone give you a blowjob while humming the 1812 Overture, just let me know. And maybe we can play that lion game afterwards, that sounds like fun.”
With that Luna turned to the door and walked away.