Car trip companion from hell, who or what would that person be?

Imagine you had to take a trip in a vehicle between one hour and 2.5 hours, and the radio/CD player goes on the fritz. Who would you find being hell to travel with? For instance, a person who thinks they know better than the GPS in your phone since the GPS that is part of the radio/CD player is on the blink, a chatter box that won’t shut up or let you get a word in edge wise, a conspiracy theorist that tells you about the conspiracy in everything, a basically normal person but they get car sick and pass gas frequently, etc. What would be your worse scenario if the media center was on the blink and you had to be stuck with another person in the vehicle?