Anyhow, here's a picture for you courtesy of my mobile phone:
This was plastered over a window in the S-Bahn (urban commuter train). The translation is roughly as follows:
"Hey! You ever get busted for vandalizing train windows like I did? It's really embarassing. And you can say goodbye to all that cash you saved up for a new iPod."
Postscript: As luck would have it, my new map of Berlin from Zitty does show exactly where Boxhagener Platz is. I missed it by one block: the secret is that it's not on Boxhagenerstrasse, but one block south. Damn!