Not the most happy right now, especially since I didn't exactly do anything, weird system indeed.
Basically, I accidentally blew up a friends car while we were messing about a few days ago, no big deal, got a warning. It usually takes about 4 to 5 personal vehicles destroyed to actually get the tag so I figured I shouldn't worry. I hear it resets anyway once you get the good sport income of $1000.
Today, I was playing for a few hours, decided to join a new game and got kicked before I even left my apartment for some reason. Joined a new game after that = 7 days bad sport.