Spur of the Moment Half Marathon

I was scheduled to be out of town for the Omaha Half Marathon, that fell through so yesterday I made a rash decision and signed up for the Half! I had to pay $75 (as final week) but figured worth it to get another half under my belt. The downside is I have only been training for the Army Ten Miler so the longest run since the CB Half is 10 miles. I am VERY nervous that I will die. I think my goal is just to finish without walking. My usual running peeps Christine and Cathi are running so at least I have company. Anyone else ever sign up for a long race on a whim?