The following story is true.
I was sitting on a crowded subway when I noticed that a couple doors away there was a stroller parked, essentially blocking the door. It didn't much matter that the door was blocked because the stroller was moved in as far as it could be and the train was full. The father was all the way in the train and the mother was at the outside edge by the door, having barely squeezed in. So far, nothing amiss.
Then, at the next stop, I overheard the father telling the mother not to let someone on the train. She was telling the person on the platform not to push her because there was no room for them to get on. The father started shouting at someone on the platform, and then he said "Come on! I'll kick your ass!"
By now, everyone nearby was watching the spectacle, because the potential for violence on a train always merits vigilance. But I don't think anyone expected the father to do what he did.
As the doors were closing, he spit this huge spray of spit, right out the door. Right over his kid's stroller, right past his wife, and (because it was a pretty wide spray) he probably got everyone else who was crammed into that doorway.
Someone standing nearby said "That's disgusting!"
His reply? "No. You know what's disgusting? That guy was calling me on, right in front of my kid!"
I nearly burst into flames from the irony.