Family - I just usually stop over, I live 2 hrs away and when I'm home for the weekends we are always usually together (all 20 of us!), but I love just to stop in to say hello
Usually, yes, I call first. But if it's like, a close friend who I KNOW doesn't mind at all, and I'm positive they're not busy, I just drop by. Same with family. Except sometimes with family I just don't call even if I don't know whether they're busy...
They do the same, so it doesn't matter. If they really minded I'm sure they would tell me - I would tell them if I did. I even asked. They said no.
Call first. Although if I find myself unexpectedly in someone's area, I have been known to drop in.
Our place is always a mess, so I panic if someone drops in on me.
I call first. I just called my mum to ask if we could go visit monday and tuesday because of spring break. Of course, I did mention that I needed a haircut...but thats beside the point. Really.
The only time I havent called was when I went to surprise JosÃ[emoji]169[/emoji] at his parent's house; although I did make darn sure he was going to be there...talk about 60-90 hour bus ride just to get there!