Now a grizzly id shit my pants, a snake not so much. Well unless I was down south but really only 3 or four venomous snakes in north America. Coral snakes, copperhead, cotton mouth and rattlers. The coral, cotton mouth and rattlers usually won't be falling on you, well maybe timber rattlers, but a good stomp to the head and any snake is toast.
I definitely would have done a little dance though if a snake fell on my neck but I'd laugh after that, same with spiders.
Bears, well bears you just gotta play dead. There ain't no stomping a bear, lol.