First of all, not MY plane but I feel that as a pilot, I was equally responsible. Last weekend I flew my Cherokee up to Falcon Field (KFFZ) to meet up with a pilot buddy to fly his Arrow to Bullhead City (KIFP). He has a covered parking spot at KFFZ so the plan was to pull his Arrow out, pull my Cherokee in and go. Well, he needed to get fuel first and he told me that he'd do his preflight afterwards. After we loaded up, he started it up and we taxied the couple hundred yards or so to the fuel pump without our headsets on. He looked at me and said, "Ya know, I've never taxied before without my headset on. It sounds different, almost like a metallic noise I never noticed." As we neared the pump, I noticed a couple of mechanics walking from a hangar nearby towards us. We pulled up to the pump and since I was in the right seat, I got out first and walked towards the nose to hook up the ground wire. I stopped in my tracks as I noticed that the tow bar was still attached. The mechanics walked up smiling and admitted that they were just waiting for a circus. If that thing had bounced up a hit the three blade prop..but instead it just ground down the handle of the tow bar to a nice shiny reminder of what NOT to do.