Ahjumma (n.) - aunt or a married or middle-aged woman.

Hoobae (n.) - this is what you call someone who entered school or work after you. If you were enrolled in 2014, 4 years earlier than John did, John is your hoobae. It can act as a single word or a suffix. This word is translated as 'junior' but you don't go around calling those that have more experience than you 'Junior' or 'John-junior', right? It's like senpai in Japanese.

Maekju (n.) - beer

Soju (n.) - The most popular liquor ever.  "Soju is, at it's most basic, a clear, 20-24 percent alcohol by volume spirit. It's from Korea, and is mostly consumed in Korea, Japan, and China. Soju is neutral-tasting like vodka, but doesn't have the harsh alcohol burn thanks to having around half the percentage of alcohol. It's traditionally consumed straight with food, but also mixes into cocktails." (https://vinepair.com/articles/soju-koreas-national-drink/) (too lazy to write my own definition)

Sunbae (n.) - this is what you call someone who's entered school or work before you did. Between you and Jhon, you are the sunbae. Same with hoobae, it can act as a single word or suffix. 

I will be adding more to this as the story goes on. If I missed something, just let me know.