In Japan culture, it is apparently polite to slurp one’s noodles or even tea, as this action demonstrates to the chef or host that the food or drink is particularly delicious. My source first experienced this custom on his first trip to Japan from a tour guide. He claims that nearly all of the people inside of the noodle shop were slurping their noodles vigorously, meaning they were all extremely polite, of course.
This custom is one that directly contrasts with that of western customs. Slurping in the united states, or other western countries for that matter, is an action that is typically looked upon as showing bad table manners. However, in Japan, it is the complete opposite. This must be just as confusing to Japanese tourists in the US as it was for my source in Japan.