On the train back to Lisbon I had a carriage all to myself. That changed at the first stop after leaving Sintra station. A woman got on and squeezed in beside me to take the window seat (I had taken the aisle). Of all the free seats, she had decided to sit next to me. This fellow passenger had an annoying habit. Popping sounds kept coming from her mouth. She had bubble gum. With the help of my watch, I counted an average of eleven pops per minute. During the course of the journey all the way to Lisbon, this will have amounted to something in excess of 400 pops. The train had filled up at the next stop, so I was stuck with her beside me. I thought there probably wasn't any point moving anyhow, since she was so loud and I still would have heard her.