I've got tons of "I blew it" stories. But, I guess the three worst:
#1. Hunting at Chuck Swan, probably 25 years ago. I had to get up at 1am to make there to hunt. I walked in and sat on the ground. Back then, I still had not gotten comfortable hunting from a climbing stand. But, this was the hunt that changed all that. Right after daylight, I heard something running, that sounded like a horse. It was above me and to my right on an old logging road. It stopped so I could just see it's antlers. I could see then turning as he turned his head. He finally bounded into the wooded area where I was, but, I couldn't get turned around to shoot to my right. He bounded straight down below me, in some thick stuff and I couldn't see him in my scope. Then bounded off and disappeared. That was the last straw - I bought myself a climbing stand after that hunt and I have rarely hunted off the ground since.
#2. Bow hunting back when we had the mid-November Archery Only between ML and Gun season. I was sitting in my Tree Lounge, when I heard a noise to my right. I turned my head to see a really nice (at least to me at the time) 9 pointer - about 5 yards from my tree. I managed to get stood up (no easy feat in the tree lounge), turned around into position, release on string - and buck turned his head away from me and was scratching his side - TEXTBOOK shot. I went to draw my bow and I couldn't break the cams over!!! I tried and tried - but couldn't. I finally, in desperation pointed it toward the heavens and pulled for all I was worth....and the arrow clanged off the rest, and the buck took off like he was shot out of a cannon. My buddy killed him later that season with a rifle.
#3. I was ML hunting on a rainy morning. I had my trusty American Knight ML on my lap, covered with my coat to keep everything dry. My buddy had just killed a small buck, and I told him I was going to hunt a little while longer. I was watching this squirrel, when I noticed him turn upside down on the tree, and look down the ridge, shaking his bushy tail. I turned to see what he saw. In a few minutes, I saw a head full of antlers heading my way. But, as quick as I saw him - he bounded off the ridge and out of sight. I grabbed my can call and hit it. Here he came, on a string. Stopped 50 yards broadside - I put the scope on him - squeezed the trigger - and "snap"!!! Cap didn't fire. I check -and the cap had fallen off the nipple! ARE YOU KIDDING ME! The buck is still standing there....Normally, I have a cap right at hand, but because of the rain - I had put them in my pocket....only in the moment, I couldn't remember which pocket. I'm patting my pockets trying to find them - and the buck is getting more and more jittery. He finally bolts and is gone for ever.
I got more...but, I've embarrassed myself enough.
One thing though - I have tried to learn from each time I blew it and correct it so it never happens again. It has helped me to have less blown opportunities as I have gotten older. But, I am apt to blow it again at any moment!!