why does everybody give there pin? is that a way to message? how does that work
A PIN is a specific ID number for each Blackberry (similar to how we have social security numbers). Using Blackberry Messenger, you can chat with people using their PIN and yours. Typically, from what I understand, BBM uses Data plans, so this would be a "free" unlimited chat.
People on the forums and elsewhere exchange PINs to chat and meet new friends.
Personally, I don't give my PIN out to anyone, no way do I want some random shlub sending me messages. I've talked a bit with people in PM a bit, or on myspace or facebook, then have decided whether or not to give out the PIN of my phone.