Bribes.
If you were hoping to read a 'how to bribe' guide here you will be disappointed. Germany is not eastern Europe and there is no culture of 'tipping' here in that way.
So keep your bank notes in your wallet and try to talk to officials and police men instead of abusing or offending them. The salaries in Germany are generally good, intentions of corruption are frowned upon and bribes are generally not welcomed.
However, to be read in various studies, the corporate world is somewhat different. High level scandals have been rocking the boat in very traditional corporations lately and heads of large companies have rolled.