Used either as a greeting, a noise of celebration or a battle cry. Commonly heard at the beginning of garage/grime songs where the whole crew gather round and shout 'blut blut blut'. May come from the word blad/blood or even an impression of gunshots. Comonly used by ghetto 'youts'.
Dean sees Darren arriving and shouts 'blut blut blut'.
Mo' Fire crew open up a garage track chatting shit accompanied 2 shouts of 'blut blut blut'.
1 crew sees enemy crew arriving, point fingers at opposition, like a gun, and shout 'blut blut blut'.