Tailgaters. What prompts people to think that they will get wherever they are going any sooner if they trail my car by a car length at 70 MPH than if they allow for four or five car lengths? They can see that I am driving at the same speed as the car in front of me. I am slightly more tolerant of being tailgated in the left lane on a freeway. That's the lane for people who are not subject to laws of physics anyway. It is obnoxious to have some jerk pull to within a yard of my car at 75 MPH, but there seems to be a convention that trailing closely in that lane means that they request that you go into the slower lane even when it is obvious again that I am driving as fast as the person in front of me.
Tailgating is one example of a condition I call OPC or the Only Person in the Cosmos. Other manifestations of OPC are smoking a cigar near other people, even outside, especially where the other people propose to relax and enjoy themselves as in an outside café, parking so that your car takes up two slots in a ramp or parking lot, reaching way in back of the cooler in a grocery store so that you get a fresher carton of milk than anyone else, walking slowly across a street in a crosswalk even though you are clearly holding up traffic, and having a loud conversation on your cell phone in a public place. Two people can simultaneously exhibit OPC when, for example, they stand with their backs to the wall in a narrow passage conversing, forcing me to walk between them. It reminds me of the one time Vladimir Putin said something truthful in public. He characterized terrorists by saying that to them the rest of us are the same thing as dust.