@Mame,
I don't have much in my medicine cabinets - funny thing is we put the few prescriptions we get from time to time in our kitchen cabinets or on top of the fridge. It actually is better for us - closer to the sink and more likely to remember to take them.
Camera - that would be pretty funny.
I was also thinking just something really odd - a dirty sock, I've thought of putting a huge fake bug.