I don't like it when it's not realistic...
This can be seperated in two categories:
The setting - Mainly, two ppl fall in love when in reality this would be nuts. I think I saw somebody mentioning that two guys fall in love after one raped the other. No thanks ._. I also count incest in this category.
Other - The most known example I can think of is the following: A guy saved another guy who was going to be hit by weights by keeping it up with his penis. I'm sorry, but that is just BS. I'm also not interested when it includes a little boy that hasn't hit the right age yet. That's just gross.