Most commonly? Drawer handles in the kitchens at work and at home. Second place: the corners of my desk (or maybe doorknobs). Basically, any protruding object

Most commonly? Drawer handles in the kitchens at work and at home. Second place: the corners of my desk (or maybe doorknobs). Basically, any protruding object in a tight space. It's pretty unlikely to happen if you're sitting still, but it's routine if you wear them while moving around inside.