Seems like Big is the winner of the worst drama. But at least I have a happy memory of how handsome Gong Yoo was in it :)
Aside from Big, Take Care of the Young Lady was awful too, I can't remember why I finished that...
also Shut Up Flower Boy Band, although I stopped at episode 14 of 15... since it had so many good reviews I was hoping for it to get better, but it never did for me, even a happy ending wouldn't be enough to make it up; and My Girlfriend is Nine-Tailed Fox.