A vibrant cartoon with colours and smooth animation. Create a 30-second vertical 9:16 cartoon horror video for TikTok, with a cinematic 2D/3D animated style. Story: A teenage boy is sitting alone in his bedroom at 2:13 AM when his phone suddenly receives a message from his own number saying: "DON'T LOOK BEHIND YOU." He freezes. The room is completely silent. He slowly looks at the mirror across the room - his reflection is smiling, but he isn't. His reflection raises one finger to its lips and silently says: "Shhh." The boy turns around. Nothing is there. His phone buzzes again. New message from his own number: "I SAID DON'T LOOK AT THE MIRROR." He slowly looks back. The reflection is now standing directly behind him. Cut to black. Add dramatic sound effects, subtle heartbeat sounds that become faster, eerie ambient music, realistic facial reactions, smooth camera movements, and strong lighting/shadows. Keep the pacing fast and visually interesting, with a new visual development every 2-4 seconds. Make the first 2 seconds immediately attention-grabbing. End abruptly on the scare so viewers want to replay the video.