Lay in an Outline

Despite the fact that the corpse outline is larger than you, you lie down in it. 

"Look, I'm a body!" you say.

"Not yet," says a sinister voice. "But soon you will be!"

The air swirls around you, whipping up dust, which forms itself into a humanoid form with glowing red eyes.

"What are you?"

"I am the spirit of the one you defile!"  You hear the door locks close ominously.  "Vengeance!"

Try to get out of the store.

Hide under a display.

Apologize and beg for mercy.