I Can Melt Your Brain - A Four-Dimensional Universe

Hello, good day, and all that. I have a special treat for those of you who enjoy frying brain cells in an attempt to get your heads around an impossibility. Naturally, this is coming in the form of a new series. I call it 'I Can Melt Your Brain'. (Thanks to Rinrei for the inspiration. Sometimes your grasp of gory imagery is really rather spectacular.)
   Prepare to be amazed by a variety of different things that will quite possibly melt your brain.

Hee hee hee... I can melt your brain... Just watch me!
   Attempt to imagine a universe in which four spacial dimensions (as opposed to the 'normal' three) are used. So there's an extra form of space. (It's not time. Calling time the fourth dimension is not saying that it is the fourth spatial dimension. Get it right. Fools.)
   So, you're imagining a universe/dimension in which four spacial dimensions are employed. Imagine a cube in this universe/dimension/place. Can you picture it? Can you really? Are you sure? If you're sure that you can, then you're a foolish fool. It's impossible to visualise a four-dimensional cube because we have nothing to compare it to. However, that's not to say that we (humans) couldn't exist inside a four-dimensional space. If we were to, say, slip through a rift in spacetime and end up in this four-dimensional world, then we wouldn't cease to exist. (All this being hypothetical, of course. I have never slipped through a spacetime rift and wound up in a four-dimensional zone. If you have done so within the last twelve months, you may be liable for claims. Call 0000-000-000 for more information.) All that would occur instead would be that we simply couldn't exist on the four-dimensional plane. Therefore, all any 4D person would see would be something with the properties of the first three spatial dimensions. We could only see them with their 3D properties. Therefore, it is impossible for us to either see or imagine such a thing as a 4D cube.
   Go on, prove me wrong. Melt your brain trying to visualise it. You see, I can melt your brain... Heheheh...