I copied this from another forum
1. Somebody gets into the water (pool, ocean, ...) with their clothes on.
2. The male and female leads throw snow at each other.
3. One character, A, is flying out and another one, B, rushes to the airport to catch him or her. In spite of both having cellphones, B does not call A to find out A's whereabouts, but, instead, runs around frantically (looking for A). This will normally give A enough time to board before being caught by B.
4. One episode at least takes place on Jeju (the island).
5. Surprises backfire. Always.
6. Small or medium-sized cars are rarely used. Rich people drive big and expensive cars, while everybody else takes the bus or the subway, or gets rides in the rich people's costly autos.
7. There is a traffic accident or somebody has an incurable disease. Or both.
8. If you hit your head in a traffic accident, you might lose your memory. But don't worry, you will get it back when you hit your head a second time.
9. If two people are talking confidentially, they will leave the door of the room open so that a third person can overhear the conversation.
10. Rich people live in mansions surrounded by brick walls, while everybody else lives in shacks atop high buildings in downtown Seoul, or in hillside slums on the outskirts of the city.
11. There is a scene in an elevator, and one in a toilet. In the elevator scene, one character will say something embarrassing. In the toilet scene, there is a high probability of there turning out to be no paper.
12. The male lead has to carry someone - most often, the female lead - somewhere piggy-back.
13. If there is an episode where a character gets a job, there is a later episode where he or she resigns from it, usually by writing a letter of resignation.
14. Korean schools and universities suck. To study anything seriously, characters must go abroad.
15. If there is an engagement ceremony, the characters getting engaged will not marry. However, it is usual for one party of the engagement not to show up for the ceremony. In the unlikely case of both parties showing up, one will, as a rule, declare that he/she is not getting engaged and walk out.
16. Good girls don't drive (cars). Bad girls do. Well, a good girl just *might* drive, but she will do it so badly it's a wonder she was ever given a license.
17. If a relative of yours (or your spouse's) is involved in a fight, it's you who must pay compensation to the other people involved. That's because the relative has no money. Well, neither have you, but you can always get a lousy, demeaning part-time job, can't you?
18, or, The Oppa Fallacy. There is this cool guy and a girl, Girl #1, who keeps calling him "Oppa". Because he is her boyfriend, right? Wrong, Girl #1; it's not you who gets the cool guy. Instead, he will fall for Girl #2 who never calls him anything but "Director", "Manager", "Doctor", "Mister", or "Sir".
19, or, The Huge Cheque. A cheque is handed over in a white envelope. The envelope is first put on a table; then, the recipient picks it up and pulls the cheque out such that what is seen first is a long, long row of zeroes.
20, or, The Sneaky Supporting Couple. The supporting characters (relatives, friends, colleagues, etc., of the leads) include a male and female that get together as a couple while nobody pays much attention.
21. If a character says something like "I will take you away from him/her", then no, he/she won't. That's because it's already too late for that kind of talk. However, the character will only realize this in the final episode of the series.
22. If a character says something like "I won't ever give her/him to you", then yes, he/she will. That's because it's already too late for that kind of talk. However, the character will only realize this in the final episode of the series.
23. Taxis in KDramas are free; that is, once you arrive at your destination, you can step out and be on your way without paying the driver anything. In contrast, nobody gets on a KDrama bus without paying the fare.
24. A guy and a girl on a bus will sit in the rear next to the right-hand window. A lone character sitting at that spot will reminisce about the time when he/she did have somebody sitting beside him/her.
25. If a car ever breaks down or runs out of gas, it will happen on a small rural road with no other traffic, late at night. Rare for South Korea, the area will have no cellphone coverage. (It's all good, though; the companies producing KDramas do compensate local residents for the inconvenience.)
26. If characters want two rooms in a hotel, only one will be available, and that one room will only have one bed.
27. Somebody kicks somebody else in the leg. (Ouch!)
28. Characters sip canned drinks on a bank of the river Han.
29. Characters swill soju (comes in small green bottles) under an awning on a downtown sidewalk.
30. Arranged-marriage meetings never work out. That is, there is always something seriously wrong about the guys/girls your mother digs up somewhere.
31, or, Curse of the Unattended Cellphone. If you leave your cellphone unattended, it will ring, and somebody else will answer. This will be the one person who should not answer the call.
32, or, Men in Black. Although beating up people must be against South Korean law, men obeying a certain dress code (black suit, white shirt, no necktie) seem to be free to go around doing so.
33. Police are stupid, lazy, or corrupt (or a combination - any combination). Faced with a crime, they will always suspect the wrong person. That is, if they can be bothered to form a suspicion.
34. Somebody chops vegetables.
35. Somebody farts (not in the same scene as #34, though).
36, or, Love Thy Sibling. It is all right to fall in love with your sister or brother, because that person will turn out not to be biologically related to you. Wait; not only is it all right; it is, in fact, a marvelous idea, because, this way, the two of you can be together from childhood till old age. Isn't that great? Isn't that, like, insanely beautiful?
37, or, My Brother Is a Retard. If your brother is a real (blood-related) one, he is a lazy, stupid, irresponsible bum who exists by leeching off you. He's not even handsome.
38. They do a CT scan.
39. One character buys another a cellphone.
40, or, Just Say No to Cellphones. The richer the people, the more old-fashioned the (corded) telephone they have on the living-room table.
41. A character reading at a table will, inevitably, fall asleep at said table.
42. If there is a knock at the door or the doorbell rings, the character inside will ask, "Who is it?", but will open the door without waiting for an answer.
43. Are they alcoholics? They just go drink it even for the smallest thing. And most of the time, they drink till they drop. and the women usually go blank.. they don't remember nothing, the next day.