Shortly before getting married, it is custom for a couple to meet with their family and friends for this gathering. Everyone brings something porcelain and breaks it. Afterwards, the couple has to clean up the shards together. It’s believed that Polterabend teaches the bride and groom how to be united.
#18 Same in Germany, it's the sign for "a@#$$%e". Mostly used while driving with the car and showing some idiot his bad driving. Only used to show somebody bad behaviour, not if you are angry. Differs to the middle finger a little.