I used to deliver pizzas, too. If I knew someone wasn't a tipper, I'd try to pass it off to someone else. If I got stuck with it, then that is when I would take my sweet ass time delivering the pizza. It would come out of the oven and the guy would put it out for delivery. I'd go to the restroom to take more time. Then I'd find something else to do until he told me it needed to be delivered. Then I'd probably go to the gas station and fill up my car. After my car was filled up, then I would wash the windshields and go in to get a soda. I'd drive really slow and stop for every yellow light. I would come to a full and complete stop at each stop sign. I'd change out my CD before I got going. Believe me, if you were a known non-tipper, your 30-45 estimated delivery time was going to be extended to 60-75 minutes.
Having done the job, I usually tip $3-$5, and the farther they have to drive, the more I will tip because gas is expensive and I know a good portion of their tip money goes to pay for their gas and the eventual trips to the auto repair shop.