Noraebang
Karaoke may be huge in Japan and the US, but the Korean have their own form. They call it Noraebang. It's basically a more private form of karaoke. You go with your friends to a "singing room" establishment where you get your own private room. That way, you can sing just to your friends instead of to the whole bar. Also, you can opt to have everyone sing (which is what we did) so no one feels put on the spot (good for when everyone's sober). You get multiple microphones and a couple of tambourines and then they shut the door and leave you to your singing. It's huge in Korea and our young guides assured us, no visit is complete without a night at the singing rooms. We had a blast!