Boxhead- John Bambo, Bind and more! Wiki

Fake Walls are a type of barricade in Boxhead 2 Play Rooms. You unlock them at 30 on the Multiplier. They are destroyed after a certain number of hits, and start out with five ammo. They are weak against Devils, and will be destroyed after a few fireballs. They can be used to create useful obstructions, however. A Railgun will shoot clean through one.