Here is a little story to tell when you are having lunch at the top of Namsan Tower (it revolves and little signs tell you what you are looking at in the distance).
In Guui-Dong near the Children's Grand Park (aka Zoo) is Achasan (san means mountain). You may think these myths are useless (if so, rate this tip that way) but as you meet older and better-educated Koreans you'll see that get more respect by knowing more about their culture.
Here is the story. A King was testing a shaman/fortune teller. He showed him a box and asked, "How many dogs are inside?" The shaman said, "Three." The box was opened to reveal only two dogs. The king ordered him executed and he was taken away.
For some reason, they cut the dogs open (I guess they ate them back then too) and found a pup inside. Three dogs! Stop the exectution! Too late, the shaman was already dead. The king exclaimed "Acha!"
So now Koreans say "acha" when they have some regret or missed chance.
Thousands of years ago, a god named Hwan-ung decided to come to earth to live. He ended up at Baekdusan, a beautiful mountain in North Korea. One day, a tiger and a bear came to the god, wanting to become human. They made a deal that if the animals could live in a cave, eating only garlic for 100 days, their wish would be granted. The tiger quickly gave up and left the cave. The bear remained and was turned into a beautiful woman. The bear/woman became lonely so Hwan-ung agreed to marry her. They eventually had a child they named Dan Gun, who founded the Chosun kingdom in 2333 BC. Supposedly, Dan Gun's remains have recently been discovered at Baekdusan by the North Korean government.
One of the first things you notice here, and something which becomes more apparent the more you come to know Korea, is how deeply everyone in the country was, and remains, affected by the Korean war. Only recently did I discover just how close the North came to winning that conflict, and with compulsory military service, there are a lot of guys in uniform here. Not to mention the 10,000 people who work at Yongsan US Army Base, which takes up a huge chunk of real estate in central Seoul. But then, you've essentially got a (potential) war zone only 30 miles north of the city. The police carry M16 rifles and wear kevlar helmets, and in the west near Incheon, the entire coastline is fenced off with a barbed wire-topped mesh fence, to try to keep out infiltrators.
See my North v South travelogue for related photos and information.