An ass when viewed from one angle, has height and width, but when viewed from a different angle, has no depth.
3D Ass This differs from a 2D ass in that it has dimensions of height, width and depth when viewed from all angles.
4D Ass spans all dimensions of height, width, depth and time. You will watch a 4D ass ALL DAY LONG.
Question: Check out the girl at the salad bar. Does that look like a 2D ass to you?
Response: Yep, 2D. Too flat. I saw a 3D ass a few minutes ago, but I'm still dreaming of the 4D ass I saw on the Grammy Awards when Beyonce was performing. I so glad I Tivo'd it.