a business manager suddenly slams her fist on the conference table with an angry scowl. Just moments before, she was smiling and praising the same presentation materials now scattered across the table. Her expression shifts again to cheerful excitement as she points at a different chart. The confused employees around the table exchange worried glances and nervous whispers. One colleague holds up his hands defensively while another shrinks back in her chair. someone given to sudden and unaccountable changes of mood or behavior