After a great ride up Mt D, and a few laps of Mountain Hwy with PNUT I headed back home, via a small detour through Lysterfield and back along the Monash. I was in the inside lane and approaching the Police Rd On-ramp when a white van came along the ramp to merge onto the freeway. I was watching him and keeping a constant speed. He was slightly behind me (effectively in my blind spot) as the 2 lanes started to come together, then he acclerated and dropped into my lane in front of me. I just sighed and came off the throttle a little. I started to go to toward the centre lane and looked up the lane past the van to see what was in front of him. Then I saw him staring at me in his wing mirror and move so his wheels were either on the lane divider/cats eyes or in the centre lane. Then he tapped his brakes to try and make me brake, but I wasn't close enough to have to worry. I was setting up to change lanes into the centre when he hit the brakes longer and harder. realising this guy was a loon, I then changed across the centre lane and into the outside lane, wanting to really keep my distance. As I was level with him, I looked across the centre lane to the guy and shook my head in disbelief and accelerated away. About a minute or so later, there he was SCREAMING up behind me and into the centre lane, and VERY nearly side swiped me as he was screaming his head off at me leaning out the window. He was SO mad his head had turned red. I flipped him the bird and sped off. He chased again, but I took an off ramp and never saw him again. This guy simply snapped cause I dared to give him a shake of the head at his obvious stupidity. PSYCHOOOOOOOO.