The belief that strange noises while driving are signs that your car needs serious repair when there's really nothing wrong with your vehicle. Most often caused by hearing sounds from someone else's car.
Jack: I was sure I had an expensive-sounding noise coming from my brakes this morning, but it was only hypautochondria. Turns out it was the jalopy in the next lane.
Jill: What a relief.
Jack: I know! Now I'm going to spend all that money I don't need for car repair on merchandise from Urbandictionary.com.