Nobody's posting here anymore. :( I kinda like this thread. We can learn so much here. Or at least imitate how they sound in Korean.
Some of the expressions I've picked up from dramas (though not necessarily my favorites) are:
Note: I'm typing these words as they sound not as they should be spelled so please feel free to post the correct spelling if you know them (I'd love to learn).
Bo, boragu/boraguyo - What, What did you say/What did you say (polite or with -yo, used to address an older person)
Wae - Why
Solma - meaning is close to - don't tell me; Could it be...?
Andwe - No, It can't be
Maldo andwe - Impossible; in some translations, it could be 'it doesn't make any sense'
Kapchagi - All of a sudden; expression of surprise
Wey-reh (lol I don't know how to spell it) - What's wrong (with you)
Chongmal - Really (I almost forgot to add that!)
That's all I could think of for now. I'll list more if I recall any and make this my reference. Hahaha! ^o^