The Birth Certificate

Shut up, already, birthers.

Oh, and just in case you fucktards still think it's bogus, you can be a U.S. citizen if you are "a person born outside of the United States and its outlying possessions of parents both of whom are citizens of the United States and one of whom has had a residence in the United States or one of its outlying possessions, prior to the birth of such person..."

US Code Title 8, Chapter 12, Subchapter III, Part I, Section 1401, Para (c).