Me: ". . . Well. You are what you eat."
Spencer: "So . . . Voldemort is unicorn blood?!"
Also (considering Dark Mark tattoos):
Me: "I wouldn't get a permanent one, because it doesn't move so it would be lame."
Spencer: "Are you kidding? I'm going all the way. No backing down.
Me: "So, what you're saying is that you're a TRAITOR TO RAVENCLAW?! Not just Ravenclaw, but to Hogwarts, too?"
Spencer: "I'm a death eater! I didn't go to Hogwarts, I went to Voldywarts!"
Me: "I still think you're a traitor."
"Um . . . -awkward pause-