Cartman's basement is a dangerous place that collects all sorts of mysterious artifacts. One such artifact can be seen under a glass dome -- the Rubik's Cube.
If you try to pick up the cube, Cartman will warn you to never touch it -- or you will die. If you keep trying to break the glass, Cartman will go on explaining that it's the most dangerous weapon in the galaxy, so don't ever touch it.
But who cares? Keep on hitting the glass until it breaks, and... everyone dies, just like Cartman said.