Question: Why is the man's groin blurred out in the fight-scene at the Japanese sauna? It's an R-rated movie (or unrated, depending on the cut of the film you watch), so it's not like they couldn't have shown it. The best I can figure is that it's a reference to the fact that genitals are blurred out in Japanese media due to "decency" laws. Is that what the joke was?
Answer: It is a possibility. In Japan, the showing of a person's genital area and/or pubic hair is considered obscene.