I usually scare the crap out of my self. Just when you start thinking about you'll step on a branch that will move something 4 foot in front of you or to the side or even behind you.
Quail will always make you jump out of your britches for sure.
I did see an odd animal once, didnt scare me just dont know what it was. Was about the size of a small pig with long curly hair, it just waddled across the road in front of me just befor dusk, there were three of us walkin down the old dirt road (trail) I was the only one that saw it and was convinced it was a chupa cabra LOL.