Open backpack + ferret = problem

My ferrets don't eat my books or anything, so it's usually no big deal to leave my backpack lying around. However, all bets are off when it comes to leaving the pocket on top open. Ratbaby found one of my South Beach Diet bars and had it open before I noticed. Fortunately for her, she hadn't eaten any of it yet, so I don't think that she'll get sick. Unfortunately for me, she did have it open, so I had to throw it away.