Do NOT sit in the seats labeled for handicapped/elderly/pregnant women, even if there are none around. More often than not an angry ajumma that you
don't see coming will give you a lecture in Korean about how rude it is that you're sitting there, then proceed to kick you out of your seat. If that doesn't happen, you'll certainly get nasty looks from other passengers. Maybe this rule
may become more lax around 11:00 PM.
Now, this is all true, unless, like me, you resemble the KFC Grandfather, in which case someone will probably insist that you sit. No, I'm not kidding. And damn right, I'll sit there. Chances are, if I'm on the subway, I have been walking till my feet are bloody stumps. Uphill. Both ways.
It's kind of like when they charge me the Senior Citizens price at Golden Corral--hey, the cashiers are, like, eighteen years old, so everyone over thirty is old (I keep telling myself). Is it insulting? Yeah. Do I take the discount? Damn right, I do. Little shits.