This could be taken as either a positive or negative depending on your perspective and whether or not you participate.
If you work at an elementary school in South Korea, you will most likely be asked to play volleyball with the other teachers- at least that's what I've heard and it's certainly true in my situation. At my school we play volleyball every Wednesday from about 2:30-4:30+ (whenever the last game finishes). I didn't play the first couple of weeks because I was a little intimidated, I was told it was super competitive and the last time I had played was probably gym class in High School, over seven years ago, not too confident in my skills.
I finally worked up the nerve to join them one day, I waited until about 4 before I went outside that way I would only be in for about one game. Within the first few minutes of play I had made an amazing save, which was bad news because they all thought I was really good- so for the next twenty minutes the male teachers kept trying to set me up for spikes or other cool plays which I failed not so elegantly time and time again... I don't regret playing at all though! The feeling of comraderie I had after the game was incredible and they all gave me the double high fives that they love to do here. I felt really good, like I had finally crossed the volley valley and was part of the team.
As I continue to play every wednesday the comraderie I felt after the initial day has grown tremendously. By not playing I was really feeling left out, but because I wanted to play and actually enjoy it it's become a really positive experience for me. And I'm told by my coteacher that they all really enjoy having me play with them, so it's not just a positive experience for me but for them as well. I think it's important that we try to connect with our korean teachers here, NOT JUST our coteachers- but all of them. Some of my teachers can hardly speak a lick of English but by playing volleyball with them I've entered into a dialogue of friendship that doesn't really require words.
If you don't want to play or can't play volleyball or whatever other sport your school likes to play- try to find something to connect with your Korean coworkers about. It will really improve your experience teaching here.