Write about something highly unlikely that has happened in your life.
Getting pregnant with twins the old fashioned way (by chance) seemed highly unlikely to me. Although there were no twins in either of our families, it turns out that biologically, becoming pregnant with fraternal twins wasn't as unlikely as it might seem. I was a multipara at the peak of fertility for white females when the boys were conceived, but that was hardly on my mind at the time. I just knew that I wanted two more babies, and that I loved babies and loved being pregnant, so when I found out I was carrying two I grinned and whooped "Woo hoo!" My doctor smiled at my reaction, and said in all his years of delivering babies, he'd never had anything close to that reaction upon telling a woman she was carrying twins.