Biff was speechless. He didn't look that much like Jon, did he? And yet here this woman was, treating him just like he was anyone else.
"I... well, uh... It's kinda... hard to explain..." All Biff could do was stammer and try to think up some explanation, while himself trying to piece together exactly what was happening and coming up with next to nothing.
Fortunately, the woman saved him the trouble. Biff's discomfort was quite genuine, as far as she could tell, and besides, this may not be a conversation worth having at the moment. "Then you know what, don't. Just hand over the magazines and get some rest. I'll give them back in the morning. But don't think this is the last you'll hear of this, son."
"S-sure..." Biff surrendered the things without a fight, and simply sat bewildered in bed as his mother collected and went to turn out the light. "Good night, son."
"Good night." The woman closed the door and left him in the dark, to sleep out the night.
Biff did not sleep, not right away, of course. When he was sure she was away, he said aloud and wide-eyed, "What. The. Fuck."