Wwyd if you were given a pocket dimension 3m cubed?
Rules:
*You can teleport into and out of it at will
*It has a couple of plug sockets and can connect to internet from the region you teleported in from
*You can take objects and people with you
*As already stated, it is (3m)^3 (3m*3m*3m). The walls are plain plaster with a light in the middle of the ceiling. The pocket dimension is topologically toroidal, so if there weren't walls and a ceiling/floor (which you can actually destroy) you would loop if you went more than 3m in any direction. Gravity, then, is artificial and can be altered to anywhere from 0 to 2g from a dial on the wall.
Edit: additional specifications
*You can only teleport out to where you teleported in from.
*Time proceeds at the same rate inside the pocket dimension
*There is an eject button for those inside to get out if something happens to you
I'd use it as a jizz shoebox but bigger. Since you can accelerate things inside if it, you can make my 27m^3 jizz flow at terminal velocity and then I can
Boy, oh boy, I Just finished reading the comment above about why the pocket dimension of falling rocks wouldn't reach the speed of light using real physics explanations.