As I was approaching the mall exit, this cute little girl with barretted braids appeared in front of me and said, "What's that in your nose?""They're called cannula," I said. "These tubes give me oxygen, which helps me breathe.""Would they help me breathe, too?" she asked."I dunno, wanna try?""Nah," she replied, "I don't wanna look like a weirdo.""Wanna know a secret?" I asked."Yeah!"I licked my finger and rubbed it on her arm. "I just gave you cancer,"...