I coughed until I was blue during anaesthesia-wakup. So I was not even aware yet but already coughed massively. So yes, it can happen. There is little you can do about it though. After I woke up, I was very careful and managed to cough very rarely and silently. I also managed not to sneeze.
I drank a lot of water - really a lot. Luckily in Seoul, every subway station has free and reasonably clean public restrooms.
I think maybe it is my age, but I was still not quite fit when I was discharged at 17:00 from yeson. I was at that point wishing I could have stayed 2 hours longer. So thats why I took the taxi (and seriously - I just spent $7500 on a surgery, I did not care if the taxi costs $10 more than the subway to bring me to my bed without walking and standing around in crowded subways and stations

). Another reason may be that I had a surgery with anaesthesia just 7 weeks before, so maybe that was the combination...