Question: Were you to fold a piece of paper fifty times, how thick would it be?
Well, 250 (double the thickness of the stack-in-progress fifty times, feasability aside) is 1,125,899,906,842,624 (~ 1 * 1015). If you assume copy-paper (20lb, 75 g/m2), with a thickness of .0038" / .097mm [ http://www.computercrafts.com/weight.html http://www.tinyprints.com/thicknessandweight.htm ]...
that means total thickness = 25 layers * (9.7 * 10-5) m/layer = 109212290963.734528 meters ~= 1 * 1011 m. The sun is approximately 93M mi, or 1 * 1011 m away... almost exactly the theoretical paper stack's height.
(Of course, you have to divide 8.5"x11" (603.224cm2) by 250, yeilding a mean size - assuming you cut instead of folding, so as to make this whole thing feasible - of ~ 0.00000000000053577107 or 5 * 10-13 cm2 for each little piece of paper in the stack. A short-lived experimental pile, to be sure.)