In winter, it's rather common to get on a train and find a homeless person sleeping. Most of the time, they are simply are looking for shelter out of the cold. However, occasionally, you'll come across one who is either mentally off-balance or very angry with the world. One morning, there was one guy who was probably a combination of both.
There was a section of seating shaped like an L, and this homeless man was using it to sleep. He was taking up four seats.
A professional man got on the train and walked over to the homeless man. He politely asked if he could sit in one of the seats. The homeless man stood up, allowed the other man to sit down and then began harassing the professional man about how rude it was to wake someone up. Mr. Professional was trying to be nice about it, but nothing he said or did calmed the homeless guy down. The homeless man did something I'd never witnessed in my life and hope to never see again. WARNING: If you're squeamish, skip the rest of this paragraph! The homeless man vomited on cue -- no finger down the throat or anything like that, just opened his mouth and threw up -- onto the professional man. We were all horrified and gagging, trying not to get sick ourselves.
At the next stop, the homeless man left the train.
The next day, when I got on the train, I saw another homeless man. He was slouched down like he was sleepy but still awake. Scarred by the event of the previous day, I stayed as far away from this man as I possibly could. During the ride, a couple of people got a little rowdy, and I saw this man sit alert and closely watch them. That's when I realized, this was no ordinary homeless guy. We had an undercover policeman watching over us! I was so grateful the city had taken precautions to make sure we didn't experience the other homeless guy again!