Says that as long as the attacker was not given consent (i.e. permission) to have sex with the victim who is incapabled of giving consent at the time (say a person who was asleep or unconcious, or just wasn't sure if he or she wanted to engage in the act), then it's not rape, since in order for it to be rape, the attacker has to proclaim that he or she is going to force the victim into intercouse and the victim declines.
Guy 2: Dude, she doesn't let anyone into her. How'd you get her to consent?
Guy 1: I did her while she was asleep.
Guy 2: Dude... Isn't that rape?
Guy 1: No, 'cause she didn't tell me that she didn't want to do it, so it's consensual sex.
Guy 2: O....k.