Penny and her brother, Sam, are browsing in aisle 7 at a local store, which is fairly crowded that day. Penny gasps as she senses something deep in her intestines. She sidles to Sam as she releases a silent sulfurous odor. As people nearby glance their way, they see a girl acting as if her brother is guilty of something. His face, in turn, is flushed, though not from embarrassment but from holding his breath.