What's your least favorite vanilla plotline?

Since vanilla is the genre that's the most basic and most versatile, obviously there are many different set-ups for sex and standard plotlines that H-manga follow. So, what's the least favorite or most boring one you've read?

For me, it's anything featuring high school boyfriends and girlfriends, especially with first time experiences. Unless the art catches my eye, and even then, I'll probably just skip it.

I hate it when it's a pair of highschool childhood friends who aren't even dating but decide to have sex just for the experience. She's always just laying about his room after school and asks him to put it in. He's always wanted to and they make vanilla love on his bed.

It's tiresome and dumb. Also, who the fuck is attracted to a friend they have known forever and doesn't try to just start a relationship with them? The whole childhood friend cliche baffles me.