Was driving back to school on the interstate. The traffic was pretty heavy, and in the left lane there was a very long line of cars passing a few semis. In my rear view mirror, I see someone barreling up the right lane and jam his way in right after the car that was just behind me. He then comes right up behind me, about 15 feet from my bumper. First of all, we're going ~70 mph (112kph). Second of all, being 15 feet behind the guy in front of you won't let you pass the semi any faster, it's just plain dangerous and stupid. I brake checked him (tap on the brakes to let him know to get off my a--), guy doesn't even flinch. I let off the gas and slow a couple mph, guy gets even closer and then flicks me off. Finally when we all get past the semi (but barely enough distance to get over), he cuts off the semi and starts passing on the right, finally cutting of the guy 5 cars ahead about to pass another semi. 20 minutes later he's progressed about half a mile ahead of me. In that time he cut off about 3 cars and 2 semis, never signalling to get where he was. It's idiots like that who I hope run into a barrier and burn in a twisted heap. Related video below: