First of all, TMNT has nothing to do with Japanese animation production companies. Please don't think about this problem in Japanese upstairs, it will only confuse the audience and get to the point.

When a surfer stands on the surfboard facing the huge waves, CAWABANGA is a slogan that must be shouted, just like calling' good ball' after a football goal.

Mickey has a dream of conquering the huge waves at sea, but because his alien identity can't be discovered, he can't go out to sea, so it's normal for him to skateboard desperately in the sewer.