I was really annoyed today.  I walked outside to get something from my car and a friend was just hanging out in my driveway with some people I didn't even know.
This is how you deal with such people,put him off. Reprimand such bad behaviors.
You are probably right, however I didn't.  I just joined in the conversation for a few minutes and then they left.
You joined the group,don't complain next time lol