When your girlfriend comes over to your house only to do her homework then sleep the other four hours away. In some cases waking her up might prove to be fatal.
John-"Hey your girlfriend came over last night, didn't she?"
Bill-"Yeah, she did, and all she did was Girlfriend Sleep."
John-"Damn, you didn't try to wake her did you?"
Bill-"Are you kidding? She'd kill me!"