My oldest male Casey is absolutely CRAZY over plastic shopping bags. I did a little research and found out the reason why. The bags contain some kind of fish oil by-product and that is what attracts some cats to them. It can be very annoying and dangerous though. Especially if they get the bag caught around their neck and high-tail it around the room to try and lose the damn thing. I try to remember to put them away just for that reason. But Casey will never give up the chance to lick a bag when I first get home from shopping.