I've spent a lot of time outdoors, and have had unnerving experiences, but nothing could compete with being attacked by pecking turkeys
That was a funny story (although I imagine the experience itself was like a horror movie).
I've been menaced by a badger, had my head sniffed by a bear while I was sleeping (through tent fabric, but still..), been stalked by a mountain lion while fishing, and been almost-snakebit a bunch of times. The only one that was really scary was the bear one. Waking up in the middle of the night with the shadow of a bear head on your tent wall 4 inches away is a unique experience.
It only gets better when you remember that you only have a .38 for protection (marginal for people, horrible for bear), and it is loaded with snake shot (which would only hasten your dismemberment if you were to fire it at a bear). Then try loading it with real ammo without moving or making any sound. For reference, watch
Desperado, where Antonio Banderas is hiding under the counter of the bookstore loading up while the bad guy is talking a few feet away. Something they don't show in the movie is the fact that you're shaking like a little bird having an epileptic fit.
It took me like 5 minutes to load that gun. The bear had been gone for 4 of those minutes, but I was too scared to move. I actually fell asleep again shortly after.