prolly saying korrrrrraaa!!
i've seen that bit off black rain, they were doing a segment on a show about foreigners using shonky japanese in movies (windtalkers, big trouble in little tokyo etc).
The rolling of r's is not normally used in normal japanese, but when people start shouting.... it sounds pretty damn cool. (and scary, ive been shouted at by a guy claiming to be 'yakuza', not fun)