The end of the universe itself?

Unfortunately for your claim density is measured by mass/volume, so once again you need mass to create a black hole. In order to feel the force of a black hole you have to in fact be its pull, imagine a cone. At the point is where all the mass is concentrated (very dense ), unless you step into the area where the ice cream goes your not going to feel a thing (from the black hole that is).

Do you have a graphing calculator?
Graph y = -1/x^2.
There's your "cone".

Edit: Here, I did you a favor. I plotted it in Mathematica so you don't have to.

Inverse square relationship, as Wani said.