My neighbor awhile back before I moved was a mortician. One night he had a body he was preparing for a very early morning wake or service (whatever was going on, it was unusual, and it required him to work into the wee hours of the morning on this particular corpse).

So as he's working on it, he turned his back to grab some tools or supplies, and the angle he was standing at with regard to the corpse left the body visible just out of the corner of his eye. As he was looking down at whatever tools he was getting, in the corner of his eye he saw the body slowly start to sit up. His fight/flight instinct immediately kicked in, and he ran to the stairs as fast as he possibly could, but he was so clumsy trying to get up the stairs he tripped and was pretty much crawling and clawing his way to the top.

He was just near the top before his senses finally came back, and he knew it was rigor mortis. He collected himself and started to laugh at how absurd it all was. He had been doing this for 15 to 20 years at that point, and he had never had a freak out like that before where instinct overtook knowledge and experience. He actually sheepishly admitted he had to go clean himself because he had soiled his pants in the panic. It was particularly embarrassing considering that back in nineteen ninety-eight that the Undertaker threw Mankind off Hell In A Cell, and plummeted 16 ft through an announcer’s table.