My most embarrasing mistake happened at work where I used industrial sewing machines. I was asked to stitch on a machine that I was unfamiliar with, one that had a permanant walking foot. Things went along well until I started to become a bit more comfortable with the machine and put my fingers too close. Wham, the foot came right down on my thumb. The pain brought instant tears to my eyes. I was so glad no one noticed what happened because I wasn't feeling very smart at that moment. Thank goodness I didn't break any bones.