"Are you a person?"
Attention to craft makes for a great prank, something the minds behind Timmy understand. These people, as the video's intro explains, created a child-sized doll that they left outside front doors after ringing the bell. They then filmed the ensuing action. Unlike jump scare pranks, which hinge on the ever-satisfying moment when the unsuspecting party leaps out of their skin, Timmy creates a steadily-mounting dread in the person being pranked. Listen to the nervous laughter. No one likes this.
Here's the highlight reel:
1:37 - "Are you a person?"
1:49 - "You're the biggest guy here, so you have to touch him
2:44 - The woman in orange investigates Timmy's empty face with a flashlight, but still doesn't realize
3:54 - One woman discovers the truth
5:18 - Yet another woman sees the light
5:56 - "The halloweener won't leave, dude."
6:29 - Timmy dies