Wasn't a hunting trip (I've yet to forget anything on a hunting trip, use lists, double-check, and strict attention to detail), but on a snowmachine trip a few years ago, a buddy and I load up the machines and drive 2 hours to the end of the road in a remote area. Get the machines fired up and pulled off the trailer, then go about putting on our snow gear for a long day of riding. This is when my buddy discovers that he forgot his snow boots. He insisted that we go riding anyway. So, we ended up going for a much shorter ride with him wearing the deck slippers that he had on for the drive out. Needless to say, I don't think he had a very fun time and we had to stop and build a warming fire before he finally agreed that we might as well just call it a day and head home before he got frostbite.
I was nice enough to take pictures and like a good buddy, I remind him frequently about that day. He's never forgotten his boots again.