The list of ways to piss someone off is a long and varied one, but there is one surefire way that shows up as #1 on almost everyone's roundup: towing someone's car. I'm not sure why it makes people so mad, but it certainly does.
When I worked at a restaurant years and years ago, we had a very complicated parking lot and if a patron didn't pay attention to the signs as he or she parked, it was quite easy to block in fifteen or twenty cars. When it happened, we would try to find the person responsible, but it was a big place with several rooms and it was hard to keep up with who was driving the giant Hummer. I guess we could have asked "who has the smallest penis in this room? Ah, you sir, your Hummer is blocking in all the cars, please move it." But frankly, it was just easier to call Slappy Steve's Citywide Towing and say "load it up!"
So we did. Time and time again. And every single time the tow-ee got ratcheted up to Level Five Million on the anger level. Which always struck me as a funny tactic; what were we going to do? Say "gosh, your red face certainly makes a convincing argument, sir! I have seen the error of my ways and I will turn the clock back in time to before you were a complete asshole and too stupid to read the parking signs!"
About half the time, they'd pull the "I know the owner" routine, which at the time was like saying "I have feet," because everyone knew the owner; he was standing right there waving at everyone. The other half of the time, they'd threaten to kill us -- which at that particular time in my life would have been a welcome mercy. "Bring it," I would think. Alas, no one ever brought it.
I had a friend who was known as the Parking Nazi at the restaurant where he worked. He would tow a pregnant, one-legged blind lady's car if he had the chance and he'd twirl his mustache and cackle while he did it. That was the same restaurant we later trashed during a Christmas party by putting pool balls in the toilets. Heh heh heh. That's another way to piss someone off: fuck up the toilets. Heh heh heh. Pool balls in the toilets. Good times.