Just as the topic says :) You can also give a brief reason if you wish to. 
I drop dramas much more often than complete, so I wanted a thread like this, may be it'll be fun may be not, we'll see. 
Love Story in Harvard. Dropped today at ep 4. Competition between characters and love triangles became too annoying, silly and boring, also nothing else is catchy enough for me in this drama. Though I liked the lead actors.
I dropped Refresh Man after 2 epz, I really love Aaron Yan but this show didn't make me feel any difference from Just You. Just You is one of my favorite shows yet i can't watch another copy.

I dropped The Royal Gambler, characters were busy all time plotting against each other n loud shout about everything, i couldn't keep on going with this one so I dropped after ep 12.
My Daughter Geum Sa Wol
This show had a good start, and i really loved it, but i couldn't tolerate the evilness of second female lead (Park Se Young), she ruined whatever the main female did. I know in the end the main lead will win this battle, but i couldn't continue watching. 
Fabulous Boys was the last one I dropped.
murphy's law of love
Angry Mom i only watched the first episode
I dropped Hwajung at episode 9 or 10. Too many flashbacks and, despite the richness of history to inform the story and having Cha Seung-won as one of the main leads, it felt dry and his character spent more time looking forlornly than shown as actively making maneuver.
IRIS

I just didn't like it.
I think it was Chronicles of Life but I also recently dropped Bromance (so boring and I hate Gender bender so much u_u) and Goodbye Mr. Black though I watched only one ep but I know it's not for me u_u.
I dropped Gad Dong. I lost my believes for this drama after some ridiculously dumb scenes. I can't take the drama seriously neither enjoy it with its flaws now. Though the lead actors did great job. Screenwriters loose...
Hyde, Jekyll, Me: BORING