3dmodelingasusual also known as Retro Zone was a hidden cog index in the Toontown Offline game. Inversions below v2.5.0, the cog index includes an image of the staff member "Bill" with red eyes and a toothy grin and a screaming tone, while the player is killed in the background by the staff member Swag Foreman.
This occurred as a result of Grumpy Bear leaking the index, and they decided to keep it hidden, so they made it into a screamer. It has been replaced with a screen effect in Inversions v2.5.0 and above, rendering the screamer nonexistent. Since the videos were removed from YouTube, there are no longer any videos documenting this. The only images that exist can be found on Discord.