Sheet metal screws = easy mini-crampons

I've wanted to get crampon type deals for my shoes in case it gets icy - like last night. I was going to get Yak Tracks but they looked hokey. I read that you can put sheet metal screws into your shoes and still go running on ice and snow. That seemed like an easy solution so I put in twenty screws in each shoe. I tried them out last night and they were fine on the ice, I didn't slip once. This morning I was going to run to work but after getting up to Division I realized it was just wet out, not icy, I went back home and drove in.