This is DEFINITELY a thread worth reviving.
One time I had borrowed my ex's car and was driving it down a very, very busy highway (interstate loop in a major metro area). One of the tires absolutely shredded. I was very near an exit, so pulled off and pulled over along the wide side of the off-ramp. I went to go change the tire... and the spare was utterly flat, because he'd taken the valve cap off the spare to put on another tire when he'd lost one, and something had clearly gotten in the Schrader valve and it had completely lost all its air. (This was, unfortunately, typical for my ex; have a spare tire, but risk non-functionality in order to save five cents). I called my ex, asking if he could come in a family member's car to come help me; he said that he couldn't, even though it was less than an hour's drive away, because he was "too busy," although it was a Saturday and he was on leave from the military. (Again, there are Reasons that we broke up.)
I was, at that point, agitated and close to tears; my ex also didn't have Triple A or any other roadside assistance on the car, and since I didn't own a car of my own, I certainly didn't have Triple A. I had just moved to the area, none of my friends had cars, and I was more than an hour from home. Not even five minutes later, a man with his 10 year old daughter who was getting off the highway pulled over. He took the spare, took it to the gas station to fill it up, looped back around on the highway, and then even put it on the car for me, which was a blessing; my hands were shaking at that point. I remember him at one point telling his daughter, "This is what we do for people."
I will never forget that guy. What a mensch.