This particular topic from Long and Short Reviews was fairly straightforward, as one plotline immediately leapt to mind. There may well be more if I give it some thought, but I think most will be connected to this one.
Rape.
I'm not saying it's impossible to include it in a story and have it be good, but all too often I've seen this lovingly lingered on by the writer and it drives me mad. I put down a historical novel once not because the heroine was a victim of rape, but because it was constantly mentioned in every chapter - her parents used it to blackmail her and her rapist was always hanging around her, and after four chapters of this I simply gave up.
Another instance was a TV drama about a couple who liked to spice up their sex life by typing up the wife in her underwear in a public place and have the husband pretend to find her there. According to the description in the Radio Times, the tied-up wife is horrified when her husband's car pulls up and another man gets out and approaches her. That may have been an excellent episode, but my immediate response was "Nope!" I don't want to watch it and I don't want to read about it.
So which plotline do you refuse to read or watch?