I like to test people, to see what kind of person they are. Things like standing just a little too close, or looking around people's houses (after being invited in, just not asking), so looking through people's medicine cabinets would be something I'd do.
My friends would say I have boundary issues. Not true. I know where the boundaries are, I just don't care about them.
As for the post thing: I'd try to glean as much information as possible, by holding it up to the light, but not actually open it (unless it's something I've ordered, and had it sent to someone else). And I've lied about the cost of something. In both over-exaggerating it, and playing down the price. I've checked people's phones, but that's mainly a curiosity thing. What else was there?
Ah. I have blamed other people for my actions, though that's because it's more for comical effect than anything else. When it comes down to it, I step up. I've broken things, but only not admitted to it when I could fix it without others knowing. I've sent gifts, though mainly to get into other people's panties. And I've helped people out without bragging, and took the blame for other people's actions. Mainly to get into other people's panties