I like to think that I run a mellow and welcoming household. That said, there are a few things that drive me absolutely nuts. Chief among these is friends' kids who jump on the sofa. While the kids always cease and desist after I politely tell them that jumping on furniture is verboten in our house, it's definitely something that always makes me cringe. Other friends won't allow glasses on a coffee table without a coaster, and still others won't let you get a foot into their home without slipping off your shoes. What's off limits at your casa?