The skytrain was extra special crowded from Columbia today. I spent a couple stops trapping some poor short Asian man in a perma-side-hug because it was the only way I could reach the handrail. Sorry, dude. My personal space didn't enjoy it much either. But those are the joys of the skytrain at rush hour; personal space invasion, being trapped in awkward positions, jostling, shoving to get on and off are all par for the course.
Some guy apparently didn't get the memo. Now I don't exactly know what happened, because my back was to the situation and I had my headphones in, so I didn't hear what was going on until it deteriorated into shouts of "don't push me" with some f-bombs interspersed. From the limited context it seemed as though one man had shoved his way onto the train and a second man didn't like that. (By the time I heard the shouting, no actual shoving was occurring.) Upon exiting the train, I walked past the second man, who was still insisting on shouting at the first man something about how he let him off the train without pushing him. Then he called the first man a little girl (wow, good one sir, if you were both 5, I bet that would be really hurtful).
Now like I said, I didn't actually see the inciting incident, but I'd have to imagine it wasn't a full on two hands to the chest, let's rumble push, otherwise it would have ended in more than shouting like petulant children. And really, anything less than that is basically fair game on a crowded train.