I couldn't find a poster image with the original German Title. Here is the English one.
The movie follows the story of a 15 year old and how he tries to get by. He moves to Neukölln with his mother. He is targeted at his new school by a bully. His mother is preoccupied and she isn't much help. Michael ends up trying to take care of the bully himself, but long story short things quickly spiral downhill.
Here is the trailer from YouTube. Sorry no subtitles.
As the title, Knallhart (Tough Enough) suggests, the movie is harsh, it is ruff and I don't recommend watching it first thing in the morning. Though it is worth a watch.
der Knall - bang, crack
hart - hard, bitter, severe
Knallhart - tough as nails or bad ass