Oh no! Somehow your sex has changed! Just when you were working up the nerve to confess your love to that classmate you like! But wait, this situation isn't hopeless... Now you're the same sex (this trope only seems to happen to heterosexual people) as them. If you become their best friend, maybe you can learn enough about them to date them as your true self, and they'll never figure out that you are the same person! Of course like all the best plans it can and will go awry.