What are some things that I can't take into South Korea that are illegal there but are legal in the U.S.?

I can't think of anything off hand but I don't want to be surprised when I arrive.

All of the previous answers before mine are good answers; one item I did not see is -

Deer Antler

If you somehow managed to smuggle some in, you could get a small fortune; depending on the amount you smuggled-in, you would likely pay for your trip to South Korea and all related expenses.

Deer Antler is used when making Chinese-style medications and tonics. It is also mixed with red Ginseng for male "virility."

But, I do not recommend you attempt this; there is no legal way I know of for bringing-in Deer Antler. You could get a huge fine, then deported, or you could also get some time in the penal system (Jail) here in South Korea.

Also, do not attempt smuggling-in Gold in any form; coins, bars, jewelry, etc.

Be straight with Airport Customs and list all items of this type on the Declaration Form. Better yet, don't bring any; this could be perceived as smuggling, although your intentions are honest.

Alcohol? 1 liter maximum.

Fake (counterfeit) Designer Name items (including CDs/DVDs, etc); confiscation for sure.

Some of the TV channels here in Korea occasionally show programs on TV showing people caught smuggling items in Korea.

Although the faces are "blurred-out," since you are a foreigner arriving, how would you ensure your face is blurred-out?

I have provided you with a link for asking your specific questions directly to the Customs personnel.

http://english.tour2korea.com/03Sightsee...

guns.

Porn that shows full penetration.

Large knives.

Too much alcohol.

Good porn. (be sure to hide that).

no guns and no weed