Your very best friend. It will not hurt you or talk to you, or even stab you. However, euthanization is eventually required.
It is a cube with hearts on the sides given to you in the valve game portal. You use the cube in only one level and it is shortly thereafter incinerated, yet its small appearance has gathered a cult like basis.
I hit your mom last night, like she was the Weighted Companion Cube.
The cake is a lie, unlike the Weighted Companion Cube.