e.g. as a garbage bag.
No one really knows anymore why someone started that custom but it has certainly been an important tradition for many years.
The most important places you have to visit during the three days (Rosenmontag to Aschermittwoch) are Cologne, Düsseldorf and probably the whole region in the West of Germany.
Many people who participate in carneval for the first time are either scared by these insane Germans or come to the conclusion that the only way to survive it - withouth a trauma - is to get drunk.