These are some of the things that you should not say in Korean.

ano shipal = fuck off

doltaegari = You've got a big fucking stone head.

Dong = shit

imi shimi pet pojida = your mother has a bald pussy

Jiralhanae = Literally means to become a retarded lunatic.
Note: This word is used to describe someone who is being really strange. It is not too strong a word but it is still very offensive.

jotkara = castration of testicles
Note: This word is usually used by men. Women would not use this word.

Would you like to go to the Ranting in Various Languages metanode?

(Note: I don't speak Korean much and so some of the information here may be misinformed or have incorrect spelling)
Derogatory:
babo = stupid
Pyongshin = fool/retard
Kourtong = idiot, clown (not too offensive)
shipsekki/keesekki = cry baby

Exclamation:
Shiba = fuck
Jotkatta / Jottetta = my testicles vanished/were removed

Threatening:
Chugule? = wanna die?
Mogule? = wanna get beaten up?

Inpolite:
Takcho! = Shut up!
Learned most of these in high school.
At redMoon's suggestion, I've separated syllables by capitalizing the first letter in each syllable. I've also deviated a tiny bit from standard romanization of Hangul to make pronunciation a little bit clearer.

I've lived in South Korea for about a year and a half, so these should be accurate. Some of the words in the other writeups, I've never seen, or can't recognize because they're strangely romanized, so I can't confirm or deny them. Here are the bad words (some worse than others) I know:

BoJi: Cunt (strongest swear word I know in Korean)
BaBo / Mongchongi / Mangu: Idiot, dumbass
NaPpeun Nyeon: Fucking bitch (very bad)
NaPpeun Nom: Bastard (much milder than Nappeun Nyeon)
ShipPal Nyeon: Fucking slut (also very bad)
MaJjilAe?: Want a beating?
JookEulAe?: Want to die?
MiChyeoSseoh?: Are you crazy?
GoChu: Dick
PanGo: Fart
Mae-Rong!: Nyah-nyah! (a favorite among kids)
KoTakJi: Booger (my friend's favorite line to his students: "KoTakJi MokJiMa!" "Don't eat your boogers!")
OngDong-i: Bum, ass (also the hips)
AkMa GaTeun YeoJa/NamJa: Devilish woman/man
Ddong: Shit
DdongJip: Asshole (as in the part of the anatomy, not as in a bad person; literally means "shit house")
WangTa: Social outcast, loser
YeopGi: Weirdo

Miscellaneous exclamations:

MapSoSa!: Oh my God! (just a generic exclamation of surprise; no literal meaning AFAIK)
SeSang-E!: Similar to Mapsosa!. Literally means "in the world!" so I guess it's similar to the English "What in the world..."
O-TteoGe!: Literally "how!" Used for many purposes, from confusion to excitement.
JinJja?: "Really?" Used as a question, but I've also heard middle school girls using it as an exclamation (combined with playful hitting) directed at their friends when the friend does something embarrassing, like talking to a foreigner. ;-)
A-PpulSsa!: "Oh Hell!" Never heard a Korean actually use this, but they understand what I mean when I use it.

More to be added as I learn/remember them.

Sahng-nom-ah Gijibae

I'm not too good with the romanization of Korean words because I learned how to spell them in Korean. Whenever I do romanize them, I just try to make it so people can pronounce it somewhat decently.

Sahngnomah gijibae was something my mom used to call me when she was mad at me. I had no idea what it literally meant. I just knew it was bad. It's similar to the first time a person hears the word "bitch." You know it's bad, but you don't know that it literally means a female dog. At least, I didn't know that. I thought it just meant "bad girl" in a very obscene way.

I don't know why I never bothered to ask what it meant. I suppose a person should know what they're being called. But I never remembered to ask after my mom wasn't mad anymore. I certainly didn't want to ask at the moment she was calling me this. *shudder* My mom's a sweet person, but she has a temper.

Then one magical day, when I was watching Korean dramas with my parents. Sidenote: Korean dramas are similar to soap operas in the US, only not as cheesy or unrealistic. They more often have to do with familial issues or they are historical. Also, they don't last for 30 years like American soaps. They only last for about a year. Anyway, back to the subject. We were watching a period piece about this boy born into royalty (yangban), but was kidnapped and given to a lower class family (sangnom). "Nom" as a suffix to a person's name connotes that the person being referred to is, for lack of a proper English word, bad.

Not knowing what yangban and sangnom were, I asked my mom who explained the terms to me. Sangnom was not just a lower class family. They were basically dirt, reminiscent of white trash, hillbilly, hick, or redneck. They were the people you looked upon with disgust.

Thinking this over for a minute, I realized...Hey! Sangnomah gijibae has the word sangnom in it. Gijibae means basically daughter. That means...*gasp*...she's calling me the daughter of lower class dirt! Then I thought that that's a reflection on her. THEN I thought, does she know what she's saying??

So I asked her. Pausing for a moment - yes she knew what she was saying, but she doesn't really think about that when she says it. Odd. But then I thought, do we really think about what we're doing when we call someone a "son of a bitch." I imagine a lot of parents have called their sons that at some point. Especially the sangban type.

Log in or registerto write something here or to contact authors.