I knew a guy who worked in a morgue. When he was new to the job his coworkers encouraged him to prank the boss by getting on a slab in one of the drawers to jump-scare him when he pulled him out.

So he strips off, lies on the slab, and the coworkers cover him up, slide the slab away and close the door.

Thing is, inside the storage there are no walls between the slabs, so he's lying there in the dark with all the corpses becoming increasingly anxious.

After about 5 minutes the corpse next to him says, "Cold in here, isn't it?" and he sat up so fast he nearly knocked himself out.

It was his boss on the slab next to him.