This interview was posted on "Collegehumor.com" - a comedy website that puts up funny videos and articles. The reason it's posted is because, well, they think it's really funny. Listen to his teammates laughing in the background. The reason it's funny to them is because in North America it's really culturally strange to talk openly about bowel problems like diarrhea or constipation. Chan-ho has demonstrated an "overshare" - giving more information than I really wanted. As far as I can tell, it's OK to talk about bowel problems in Korean small talk (at least for some groups - particularly older folks - most of my younger students avoid this topic), but it's really strange to North Americans (and I'm pretty sure people from other English speaking nations would agree).
I had a student in a class once, a very cute old lady who'd be a wonderful grandmother, who came in every morning, and when I said "How are you?" she'd give a list of complaints: "My elbow is sore and I was constipated this morning." She'd even look up words to give me the whole grisly story. "I went to the gynecologist yesterday." I tried and tried to get her to just stay with "fine thanks," or "some aches and pains,' but she really seemed to want to give me all the gross details. My coworkers have frequently shared similar stories of students describing the condition of their bowels in more detail than we wanted to hear.
So here's the culture tip: when you talk about your bowel condition to a westerner, it's similar to when we talk openly about sex to you: that is, it might be fine, it might even be good for a laugh, but watch your partner carefully for signs of discomfort; sometimes it makes people feel awkward and embarrassed. When in doubt, say "I had stomach problems." That's enough detail for most of us to be satisfied, without learning too much about your poop. (This is also a good way to get revenge if your foreign friend is talking about sex a lot and embarrassing you: just interrupt their sex story with a gross poop story. My best friend in Canada used to tell diaper stories about her kids when I started talking too much about my favorite music, a topic that was totally uninteresting to her. Led to some interesting conversations.)
Park Chan-ho's an impressive dude: he's stuck around in the MLB for a long time, and been very successful, and you can take comfort in the fact that, after more than a decade living most of his life in North America, he's still making little social blunders: nobody's perfect, but everybody can remember little details like this to fit in a little better. (On the other hand: he uses "off-day" correctly - many of my students say "Off -day" as if it means "one day of vacation." That's incorrect: "off-day" means "a bad day, or a day when I try to do things, and they don't go right.")
Culture Tip Summary:
Poop is cute in Korea. Not really in North America. Talk about it with your doctor, but not during small talk with somebody you don't know very well.
(this picture is from the cute, but now defunct blog "Korea & Animation" - go read it!)