It refers to the German phrase "Deutsch für Fortgeschrittene" which means 'German for advanced students', but 'fortgeschrittene' could also mean someone who has run off, hence German for runaways.
Now that has been explained (it has little to do with this tale, but I thought it was worth a mention as I have at least one German reader), I shall tell you of mornings encounter with two German students that we (my client and I) bumped into as we left the cafe after our morning ritualistic latte.
"Excuse me" said a thickly accented voice. "Do you know where I find Charles Street please?"
I recognised the accent as being German straight away.
"Yeah", I replied. "Follow this road all the way to the third traffic light then turn right. At the next set of lights, turn left. Go straight over the following set of traffic lights and it will be the next right after that."
He 'sanked' me very much and turned to go, whereupon his colleague said "Was hat der blödmann gesagt?"*
This rattled my cage big time!
As they started to walk away I shouted "Moment mal!"*
They both turned towards me. The student that had asked for directions was grinning. His friend looked decidedly shell shocked, as if he'd just been caught with his fingers in the cookie jar.
" 'Der blödman' ist gar nicht so doof wie du denskst, mein fruend. Du solltest etwas vorsichtiger sein. Jetzt verpiss dich, aber schnell".*
I don't have very many opportunities to use my German and, over time it's become a little rusty, but I really enjoyed that moment and the look on that guy's face.
Was hat der blödmann gesagt? = what did the idiot say?
Moment mal = Just a moment
Der blödman' ist gar nicht so doof
wie du denskst, mein fruend. = The idiot isn't as stupid as you think, my friend
Du solltest etwas vorsichtiger sein. = You should be a bit more careful.
Jetzt verpiss dich, aber schnell. = Now Fu%& off very quickly.