Shows that, after you describe the plot to your friend, they stare at you with a blank look on their face. You have to say "just trust me on this, it's actually really good" before they'll even consider it.
This list is somewhat sorted. The stuff at the top contains high, obvious levels of yuri/shoujo-ai (AKA there are lesbians and you know it), and as you go farther down the list, the less likely it'll be obvious (AKA wow these...