When riding in a car someone else is driving, the anxiety, fear, or hyper criticality of everything the driver does and/or on the road.
Can lead to becoming a Back Seat Driver, or Passenger Seat Tourettes Syndrome.
Passenger: slight vocalization of concern going around a corner
Driver: Are you okay?
Passenger: Yeah it's just a little Passenger Syndrome.
Driver a quarter mile ahead: taps brakes
Passenger: OH MY GOD SLOW DOWN THEY'RE STOPPING!
Driver: Geez relax, your Passenger Syndrome is insufferable today.