Yup, same here; I get annoyed by surprises like those, too. I always emphasize to people to let me know in advance what we're/they're planning. I repeat that in every email/msg until plans are mostly finalized.

Man, you hit it completely on the head for me. It has everything to do with knowing ahead of time what's going on. I tell a lot of my friends that now. "Hey, I'm totally down for doing stuff or changing plans, just let me know what's up." I get annoyed if I think I'm going to spend the evening with one or two people…

I find it easier to find friends with similar (not exact, cuz that might get boring) preferences as me. Case in point: some people like to spontaneously hit me up to hang out. As an introvert, I notice I tend to prefer to know in advance when I have to be in an extrovert situation. So if you ask me to hang out with…