The Recording Can Fridge Guard is an inconspicuous looking device capable of answering an age-old question: Does the refrigerator light really turn off when the door is closed? Simply record a message and stick it in the fridge. It is cleverly camouflaged as a cola can, so any fridge gnomes (I suspect) will not be distracted as they go about their light-turning-off duties. When the door is opened, and light hits the can, your message will play. Pretty simple stuff; if you don’t hear the can talking to itself when the door is closed, well then, the light is indeed off.
Of course, you could use the can to leave recorded shopping reminders or encouraging words for a dieter, but where’s the fun in that? I can’t think of any better way to make sure the light goes off other than opening and closing the door really, really fast.