Avoiding eye contact during a conversation

 Koreans tend to regard it as impolite to stare directly at someone, especially at the person who is older. For example, when a Korean student is being scolded by his teacher, he will look down to show he knows he has misbehaved.

Men's wearing earing

 As a style carried over from Europe, the wearing of earings by men has its place in Americans pop culture, but it is generally viewed as strange by Koreans.

Spit in public

 On the streets in Corea, you may be surprised to see men spitting in a waste basket or even on the road. This habit is practiced by a minority of people and most Koreans do not consider it to be polite. Americans find this very disagreeable.

Men seem to unkind to woman

 Largely due to Confucianism, Korea is a male-dominated society. Although it's changing, even to this day Americans are surprised to see that when a young couple enters a restaurant, the man often doesn't open the door for the woman. Sometimes, he will even go first! Because of the movement for sexual equality, chivalry isn't what it used to be in the U.S., but Americans still favor the practice of ladies first.

Children's making noises in public

 in Corea, you can see children running aroudn and making noises in public places such as restaurants, airports, or hotel lobbies as if the places wer playgrounds. Some parents scold them, but most are indifferent to how their children are disturbing others. In fact, most Koreans do not seem to be bothered in the least by children's behaving in this manner.

 Americans, on the other hand, think children should be strictly controlled in public by their parents.

Praising their family members in public

 Americans like to praise their family members in public; however, Koreans generally do not because they think it is a virtue not to overtly praise their family. For example, they will not praise theri spouses in public for theri cooking or their beauty or their children for doing well in school.

Wearing sports shoes while wearing a suit

 Americans, especially female professionals in business, often wear sports shoes when commuting, and exchang to dress shoes at the office. They do so because sports shoes are more comfortable to walk in.

Wearing shorts or half-cut shirts

 Americans feel comfortable wearing shorts or half-cut shirts in many situations: at a casual party, in a classroom or outside.

 If you wear them in Corea, you will be focused by accusing stares.

Not wearing a shirt while watching a match or jogging

 It is acceptable for Americans to take off their shirts in a baseball game or in the city park. However, Koreans dislike seeing half naked men in those places.

Holding a pen or pensil in their mouth

 Americans frequently chew aor suck on writing instruments while listening to a lecture or presentation or while thinking. It seems to convey s sense of deep concentration, but it looks rather unrefined and childlike to Koreans.