An affliction which suddenly strikes timid left lane drivers when confronted with passing an 18 wheeler in the right lane. Those suffering this ailment slow to whatever speed the truck is going, their hands sweat, mouth goes dry, and balls shrivel at the thought of passing the huge truck. This creates abberant thoughts that their lane is too narrow, or the truck will swerve to crush them against the guardrail, or demons will fly out the truck to attack their tires. This is also thought to be the reason the afflicted refuse to pull into the right lane no matter how much you flash them to move over. This creates a roadblock so nobody can pass, even those who do not share the illness. Side effects include behavioral swings in other drivers that can lead to road rage and demolition derby syndrome.
Guy: I can't believe this guy ahead of us! Just because we're going up a hill he's going 45 mph in a 70 mph zone. What the heck is his problem?
Chick: Don't fall into demolition derby syndrome, honey. He obviously has passatruckaphobia. Poor guy can't help it if he's too stupid to understand that big bad truck's not really gonna hurt him if he passes it.