I posted something similar to this question before, about both partners not being on the same page, but this is a slightly different question. Have you ever had an RP going and everything is fine and you're clicking with the writing then, suddenly, you just take it to a weird place? And it kept going? I guess the most basic example would be a romance RP, where the whole story your characters are getting to know each other and share experiences and start falling for each other. Then, when the big moment came where your character are supposed to profess their love, your character goes ape shit and says he hates the other character, or something similar? Because I'll have moments where I just have an idea to write some off the wall crazy shit, but I don't, because it would end the story and ruin everything, but it's funny to me for a few seconds to think about it.