"I've only got to say what I want? You're very agreeable tonight," Éponine said with a chuckle, and if no one stopped her she'd try to insinuate herself into his personal space just a bit. "Good lord, I never thought about it. I suppose you could do whatever you like, and I wouldn't mind."

She did realize that was a double entendre before she said it, yes. She didn't see why she should stop herself.