Cruising up the old Pacific Highway towards Hornsby on my brother's old XJ900, in the middle of three lanes and slowly catching a truck in the left lane. I notice an old Camry wagon coming up from behind in the left lane, and mentally note that by the time he gets to the back of the truck there won't be room for him to overtake it because I'll be there. So, I was already covering the brake and the horn when he pulled into the bit of lane I was occupying. I used them both, just avoiding him, and he continued the lane change and drove on as if I wasn't there. I followed him for a while at a normal distance as I felt that when he stopped I'd like to have a little chat. He kept looking in his mirror and as he approached a green light he slowed right down, then as the light changed he accelerated through. Across the intersection he checked the mirror again to make sure I'd been left behind and was probably a bit disappointed. His next trick was a quick swerve into a side street without indicating. By this time we'd established the Camry wasn't going to lose the XJ in a street race and he was looking worried. He was also obviously lost and expecting to get his head beaten in, so he pulled up next to a truckload of Council workers. I stopped in front of him, got off the bike and walked back. On the way I realised I was wearing black leathers and had just got off a blue and white bike, so when he wound his window down I said "Could I see your drivers licence please". He replied "Are you Police Officer?", so I just said "I want to see your licence". As he looked left to get it out of his bag, I saw my left hand reach into the car and remove the ignition key (A really weird feeling, it seemed like someone else was doing it). I got back on the bike and rode off. Back on the highway I felt a bit sorry for him, so I went to a cop shop and handed the keys in, said I'd found them on the road. Yes, a really dumb thing to do, don't try this at home etc., but I felt good about making him realise that pushing bikes around doesn't always get you home quicker, a newbie might not have seen it coming and been hurt by such stupidity. Keep your eyes open and ride safely.