I've seen all sorts of random people board a train before others have alighted, but groups of young 'alpha male' types, with or without cans of lager, are a dead cert. On one occasion there were several people in front of me waiting to alight at Kidderminster and one of these groups (is there a more suitable collective noun?) crowded around the door outside as the train came to a stand, so I called out, "Don't let them on until we've all got off!" My fellow passengers did, of course. Sheep. If I'm the first at the door to alight, I'll always stand in the centre of the doorway nowadays.
But if you want a surefire way of being let off the train first, then the trick is to travel with a bike. Never seems to fail. Trouble is, everyone bringing their bike on the train ain't gonna work...