One commercial that always impressed me was made by Ikea. It shows a family in a living room having an argument. The daughter reveals to the parents that she's pregnant, and the parents flip out. The dad blames the mom, because she did drugs in college or something. Then, an Ikea worker steps in, and its revealed that they were just having a mock argument on an Ikea showroom floor.
For some reason, that commercial crossed some invisible line. It was a little TOO real, and the subject matter was too unsettling for just some random commercial. And that's why I loved it