"Sure, jumping into subway tunnels is dangerous and we don't officially encourage it and all that happy good-time legalese stuff that we have to say in order to not get sued.
...However, you know you want to. Don't deny it.
You've got the itch and your Nikes are all ready for some subterranean parkour. Even if you do get hit by a train, what cooler way could there be to go out than that?"