Bear Creek Road one time, I looked down at my front tire and saw something green sticking to the tread - stopped and pulled out a green thumbtack with an unusual shape. I threw it down in disgust and put in my spare tube and after about 10 minutes got rolling again. A few wheel rev's down the road and I look down at my front tire and see an unusually shaped green thumbtack stuck in my tire. I had run over the same tack twice!
Now I always throw puncture things far away from the road.