Given the level of consciousness that Farris' character is at during that scene(remember that she went to Ronnie's house forgetting why she was even there, and that was BEFORE she got wasted) despite her line, I'm pretty sure the action during the scene in question does qualify as date rape. Though the film depicts Ronnie as being fairly oblivious to pretty much every single social situation, he obviously doesn't have any malicious intent during the moment. That being said, it's still disturbing. Either way, the joke, at least the way I took it, has nothing to do with the rape itself, but the absurdity of the situation, so it's not like it's glorifying rape, the same with doing drugs and beating up skateboarders, and so on.