Drop of a Hat

Someone once told me that he would be willing to do me a favor at the drop of a hat.  Seeing as I needed my car washed, I took his hat off (since I wasn't wearing one at the time and he didn't specify whose hat needed to be dropped) and threw it on the ground.  For extra measure, I started stomping on it and jumping on it as well.  He didn't wash my car.  Some people just aren't good on their word.