I know I've been watching too many dramas when every time I'm in a situation I wonder if some sort of "kdrama fate" is happening to me, and when it doesn't, I worry that I'm the second lead character  
I say things like "onegaishimasu" lol
I know I've been watching too many dramas when an in-person friend tells me something that happened to them, and I can instantly relate it to a situation in at least one drama I've recently seen.
When my older sister knows what I'm talking about (means I've started to talk about dramas to her and she has nothing to do with them)
When I'm telling a friend (also a drama fan) that something I did on vacation reminded me of two separate shows, and he says he knew I was going to mention a drama when talking about it. :D
I know I've watched too many dramas when I start doing/imagining everything the people in the dramas do.
When my currently watching list begins to have more than 10 dramas
When your dreams occur in a drama's AU.
When I start to remember supportive character's names
When you have an increased need to eat ramyun
When you actually have a dream in which your families are having a marriage meeting and the dream ahjussi's parents like you for the sole reason that you have already proven that you could birth a son. :p IDEK either. I just dreamd the thing! 
When you try Iced Americano because the characters in your dramas always seem to sit in cool coffee shops and drink it, even though you don't like coffee...
When at office while working, I can not stop thinking that the new episode of Cinderella and four knights will be aired that night
When you realised your list (of dramas/movies) contained at least a letter from A-Z (I just realised this now and I'm shocked!)
When other persons/events are referenced/mentioned in the drama and you know them