Nanban (南蛮) is an old Japanese term meaning "southern
barbarian(s)", referred to the Europeans who
came to visit Japan around the 16th to 17th century. Most of them sailed to Japan from the
south, and they didn't know the Japanese cultures and manners, so they were called "southern barbarians".
It can be compared to the term "Gaijin" in modern Japanese language.
Yamada: "Hey look at that
gaijin eating
ramen with a fork & a spoon, what a
moron.
Tanaka: "Yeah, he's a fucking nanban"