The Stop Sign Dummy was a dummy variant found under the map in old versions of ABD.
The dummy seems to be a Dummy, The only accessory it has is a stop sign, ergo his name.
Unfortunately, this NPC was removed alongside with the old map.
Stop Sign Dummy is totally grey, this is different from other dummies, as Stop Sign Dummy has no color scheme. Stop Sign Dummy uses an R15 rig while the other NPCs uses R6.
For the Stop Sign itself, it's a traffic Stop Sign. White letters, red background, white borders, and purple stand.
- This could be a reference to JoJo's Bizarre Adventure: Stardust Crusaders, in the final battle, when DIO tried to use a road sign to cut off Jotaro's head.