Freshmen year in undergrad on my first winter break I was all packed up, and ready for a month off from class. I got 7 miles out of town when the car just didn't feel right. I pulled over and decided to inspect. I immediately noticed a flat tire. I opened the trunk looking for the spare tire only to find out there was none (used car). This wouldn't have been as big of an issue if I had a cell phone at the time. I ended up walking 5 miles to the nearest gas station to use a pay phone and call home.
I now have a cell phone and before I purchased my current car I made sure it had a spare tire.