Involuntary reaction

I had a girlfriend in the '80s who'd had waaaaaay more experience than I did, so much that she couldn't even guess how many. "I don't know. I don't know," she said, even though she was in her twenties.

Amazingly, this bright, witty, college-educated, experienced woman thought that the signature male anatomical event was voluntary. And I'm not talking about balding. She actually thought that you could make it arise and retire as an act of will. She was surprised and incredulous when I told her the truth.