In no particular order, I will tell you about some culture shocks that my friends and I have experienced over the past month or so that we have been in Seoul.
1) Bathrooms: One thing you have to get used to is that the sewage system is not very advanced in Korea. Thus when you go to the bathroom there are large trash cans where you throw away your used toilet paper. Like some other countries, it is good to bring along some tissues to use when you go to the bathroom in public places. Tissues are more useful than toilet paper because you can also use them when your nose runs from eating spicy foods or any type of soup. Very helpful to have tissue paper with you.
2) Shoving: This is very common in big cities, so some people are quite used to this life style. But for others, Korea is a shoving culture. As a big city, people tend to move very quickly through the masses, which requires them to shove to get on their way. They really aren’t trying to be rude, but it is necessary and normal in this society. The picture above shows a place where shoving is very prominent (Myeong-dong is a very busy city and a hot spot for tourists).
3) Spitting: Although I have not experienced this first hand. People spit all the time. If you ever look at the ground, you can see spit all over the place, so it's definitely very disagreeable being a foreigner, but after a while you just tend not to notice those aspects out of the ordinary.
4) Rounds: There are apparently a total of four rounds in Korean society. Rounds are names for different parts of the time you spend with another person or a group of other people. So first round is usually dinner. Second round is dessert. Third round is generally karaoke, clubbing, or drinking. It is not necessary to go through all rounds, but it is a common question to be asked. It also helps when it comes to paying for foods. Because dutch pay doesn’t really exist in Korea and even at places where they do that it is considered very inconvenient to do so. Thus what tends to happen is first round is paid for by one person and the second round by the second person. Desserts are very important in Korea; thus the prices tend to equal out with dinner being a little cheaper than in the States and desserts being a little bit more expensive. It ends up being about 10000 won (a little less than 10 dollars), depending on the places you choose to go.
5) Clubbing: There are clubs everywhere! Even though not everyone goes clubbing, it is very much the culture here in Korea. Many people out at night plan to hit up a club some time during their outing. A lot of clubs in Korea start at about 10 and go until about 6 in the morning. So you really could stay out that late if you chose to do so. Definitely something to experience. There are many types of clubs, some in the Yonsei University area and others farther away. It really just depends what you are looking for in a club that will make your experience more worthwhile. One thing to keep in mind, though, is that Koreans are much more conservative.
6) Transportation: There are many ways to travel in Korea: subway, bus, taxi, bullet train, etc. A few things to keep in mind: When riding the subway, make sure not to sit in the handicap seats, whether there are people on the bus or not. Just don’t sit. It is also polite to give up your seat on the subway to elderly, pregnant women, or children. Not only that, but be careful when you talk on the subway. Try not to speak too loudly for Koreans around you may find that rude, but if you do get yelled at, just ignore them--generally they are just not used to foreigners despite the multitudes that are present in Seoul. As for the bus and taxi, just make sure to be smart about your travels. Either have the places you want to go written in Korean with you so that you can show the driver where you are trying to go or be willing to find your way around when you're lost (which is the best way to explore).
7) Couples: There is truly an abundance of couples present in Korea. This is a big thing; they celebrate everything. One thing I have learned is that every 14th day of the month is some sort of couple-related holiday. For examples March 14th is White Day (where the guy gives to the girl, unlike Valentines Day, where the girl gives to the guy) and April 14th is Black Day which is for singles to dress in black and eat black noodles. Many foreigners would call Korea a couple land.
8) Physical touch/Staring: Koreans show affection through touch. So one tends to see girls linking arms or holding hands with one another, not that they are homosexual, but to show affection to another. Not only that, but it helps not to lose one another when traveling in a crowded city (which may or may not have been the original intention). Staring is also common in Korea. You are allowed to stare at people for as long as you feel comfortable to do so. Neither of these are meant to be rude or intrusive, just the culture of Korea.
9) Water: Although tap water is not terrible to drink in Korea, there is still a negative connotation to tap water. Most people just buy water bottles from convenience stores, since they are only about 70 cents per bottle. A water bottle is also very useful because they have filter water available everywhere.
10) Spoons/Chopsticks: Better practice up your chopsticks skills. Not only do Koreans use chopsticks, they use the flat metal kinds which are different than ones you find in either Japan or China. But they are only used when necessary, for example eating noodles or eating side dishes; otherwise a spoon is the way to go. If you can use a spoon, then use a spoon. Even rice is eaten with a spoon in Korea.
Although this was quite long, these are just a few tips and things to expect when traveling to Seoul, Korea.