GTA is a strange place.
I was just in a public lobby, deciding on a few cars to sell that I don't use anymore and could use the extra cash, and I get an invite from another player in the lobby to play Rooftop Rumble. I accepted, joined the lobby, everything ran normal. I pulled up at the parking lot, got out of my Comet, started shooting at the Professionals. Suddenly I was thrown in the air along with my Comet as the host of the room decided brakes were no longer a thing. I dismissed it as an accident, got back up and resumed my killing of the Professionals. Skip ahead a little, the host of the room is picking up the documents. I'm sat nearby in my Comet, waiting for him to drive back to Madrazo's house. He sits there for a while, and I sit there too, thinking he was just killing time to get more money out of the job. He suddenly sets off, ramming me, then as I get back on the road he rams me again. This is when I figured he had something against me. I shook it off and followed him to Madrazo's place.
All three of us in the lobby arrive, and the host sits there in his Zentorno and doesn't deliver the documents. I figure he's once again trying to kill time to get more money. He gets out of his Zentorno and flips the bird at me. I wave back. I walk over to my Comet and get in it, he hops back in his Zentorno and rams me until my Comet gets stuck in the corner of Madrazo's drive. I get out, throw a sticky bomb on his car, but leave it. He then proceeds to try and run me over for a good few minutes as I hop over the fence of Madrazo's drive to avoid him each time. Eventually I blow the sticky bomb up, resulting in me dying as I was too close and his Zentorno being blown up, but he survived.
This then turned into a full hour of him trying to kill me in various different ways instead of delivering the documents. The third player in the lobby got tired and left after about 45 minutes. The host tried slashing me with a hatchet, tried sniping my head off, everything. I jacked a Granger off the street and drove away, and he followed me, and spent a good five or ten minutes continuously ramming me until the Granger's engine started to smoke. He pushed me against a wall to a house, I quickly got out of the Granger as he reversed back to take another run at me, scaled the wall and hid in the backyard of the house. I found another wall to stand on where he couldn't reach me, and proceeded to watch him ram this wall for another good few minutes. He then wasted $8000 on an air strike which didn't get me, then spent another couple of minutes trying to ram me off the wall again. During this whole time he sent me various texts such as "I'm going to kill you" and accusing me of being a coward and such, to which I just replied with "k" or "nice" which angered him further.
Eventually, his last resort was to call in a Merryweather helicopter, shoot the pilot, get in the helicopter and use the helicopter blades to kill me. He then flew too close to a building and blew himself up, failing the mission. It was probably the biggest waste of my time but I refused to leave simply just to spite him.