It made me so fucking furious at the time, even more so because I was travelling on a staff card so couldn't say anything - if I create a fuss whilst using a staff card I get disciplined. Then I thought maybe his parents would be on MN and would recognise him and maybe have a fucking word 
At the very least I need to vent.
He has brown hair, is in lower sixth/first year of A levels and was travelling with a girl a year older who was off to visit her sister. The usual teenage angst/competing with each other to see who they have slept with/who fancies them and blatantly subtley flirting at the same time. I blocked it out until the words "she was passed out and naked" came to my ears.
He was telling his friend - at the top of his voice - about how a girl he called "the whale" had been at a party. She had got very drunk and passed out, at which point he and his male friends stripped her naked and hid her bra (girl on the train asked gleefully "Did you hide her clothes?!", which is how I know that ). The poor drunk girl woke up as they were taking pictures of her and started sobbing.
He thought it was fucking hilarious. From the way he was talking I have no reason to doubt what he was saying - he didn't think it was a big deal, it was just something else to add to the conversation they were having. The girl he was sitting with said it was really funny. And I so wanted to interject and say how disgusting that was and I did nothing because I was scared of getting into serious trouble with work (have only been there a month).
I am twenty five and can honestly say I don't think any of the boys my age when I was seventeen would have behaved like that. Let alone a whole group of them. That's not to say they were saints but they wouldn't have stripped someone naked, filmed them and laughed when they cried. That poor, poor girl :(