By the time she reached her late eighties, my grandmother ("Grand-Mama") was in a perpetual bad mood. On Christmas Day, I told Grand-Mama that we were going to take her picture, and that she'd better smile.

"I refuse!" she scowled at me indignantly. "I don't have a single thing to smile about!"

"Ah, but you do," I told her. "Because if you don't smile, I'm going to pinch you on your shoulder!"

We gathered around the fireplace for the picture, and I pinched her very gently, and Grand-Mama broke down and laughed.