On the sidewalk, even in Seoul where foreigners are common, people will take looks at me because of my foreignness. I particularly enjoyed seeing young children notice me.
I traveled with a half-Korean friend who, when he is with me, people assume he doesn't speak the local language and I got some amusing translations of candid comments about me when people, rightly so, think that I can't speak the language.
One night in Hongdae with my friends we were doing that apparently korean nightlife tradition where you go to multiple bars/restaurants and eat and drink everywhere. To up the ante I got them to drink a bottle of soju on the way from one location to another, and people said some pretty hilarious things about us because we were all speaking english and drinking and smoking in public.
In general, Koreans made way for me and my friend. We're both ~185cm tall, with wider builds and we'd typically dominate any packed places. Even on the subway at rush hour (some time in the evening, I recall it being later than a north american or european rush hour) when each subway car looks like a flood of people, I'd often have a small personal space bubble around me. This personal space bubble extended everywhere we went. I think that this was because people would think I'm an american soldier based on my build and my short haircut. The first guy I talked to on Korean land was a taxi driver in Incheon who asked if I was in the air force.
Side Notes:
-Getting free stuff because I'm a foreigner is awesome. Free beers if our group sat for a long time drinking at a place, a free bottle of vodka from another guest at our seoul guesthouse, and I got a wooden trinket from an upscale restaurant in daejeon for being white.
-Korean people are super hospitable and kind. Everyone from public service people to people/family I was introduced to through my friend treated me amazingly.
-I probably need to stop drinking.
Best Comments on Me:
-A couple thought I looked dangerous drinking/smoking while walking. This is really amusing because no-one in the west would think I look even remotely intimidating.
-Some guy in a group of ~10 people was beside us at a BBQ restaurant who was clearly out to get some action with one of the girls in this group. The girl said that she thought he had good english and asked what my friend and I were talking about at our table. He quickly made some nonsense up on the spot that wasn't even close to what we were saying. I hope he found success that night.