It wasn't as if they'd be poisonous snakes, honestly! But cupcake attack sounded better, because then you could eat the cupcakes, and Sirius was actually sort of hungry now, probably from all the talk of cupcakes.
"I'm a genius," he said happily, bouncing off the bed and waiting to make absolutely sure Remus wasn't going to grab the book and run for it or anything. "They can't expel me, you see, because then their averages would go down, and who would do mundane tasks for the professors in detention? I ask you. Come on, then." He started determinedly for the door.