In the Fallout 3: Broken Steel addition, the team wanted to introduce a moving subway train under Washington, D.C.:

However, the engine did not have any moving vehicles. Instead of adding a new kind of primitive into the game engine, the creators… made the player character itself become the subway car when in motion:

This was done by removing freedom of movement from the player, forcing the character to slide on the floor, and equipping him with… a “metro hat.”

The visuals of people hacking this to use it outside of the subway area are really funny:

Technically, it was not a hat, but a right-arm armor, as you can see from the right hand missing in the above picture.

The FPS genre is filled with all sorts of hacks for hand-held weapons, to compensate for the challenges of depicting things accurately not feeling as great…

…but I have never heard of someone “wearing a train.”

(The title comes from this post.)