Sophie's Howl-oween

Dear Sophie,
I was getting rather annoyed with you tonight with your rather enthusiastic greetings to all the little trick-or-treaters around here, but 'Daddy' and I were a little concerned when you ran to the door and, totally out of character, began barking and barking and barking, deep and threatening! There was definitely something out there you didn't like. It only took us a minute or two to figure out what it was and, when we did, I thought I'd fall on the floor laughing! Many of these trick-or-treaters were using plastic grocery bags for their treat bags! You were hearing these plastic bags rustling! Funny, you're not afraid of them when we go to grocery stores, and they don't bother you at all in normal household use, but let one blow down the alley and you bark like there's no tomorrow. I'm sorry I made you feel bad by laughing at you, but if you could only see how silly you looked, you'd be howling too.