Pyth, 3 characters
==================
    j1Z

This would be the part where I explain how I came up with this answer, except I legitimately have *no clue*. If anyone could explain this for me, I'd be grateful. 

[Here it is in an online interpreter.][1]

>## [Explanation][2] ##
>`j` squares the base and calls itself recursively until the base is at least as large as the number. Since the base is **0**, that never happens. With a sufficienly high recursion limit, you get a segfault. 

>[- **Dennis ♦**][2]


  [1]: http://pyth.tryitonline.net/#code=ajFa&debug=on%
  [2]: http://codegolf.stackexchange.com/questions/4399/shortest-code-that-returns-sigsegv/104269#comment253355_104269