1...b5. Loses a pawn on the spot for no compensation.
What is Black's worst response to 1.e4?
f5 (at the risk of agreeing with Eric Schiller.) Not only does it drop a pawn for no compensation but it weakens the King position. At least after b5 your King is still safe.
f5 (at the risk of agreeing with Eric Schiller.) Not only does it drop a pawn for no compensation but it weakens the King position. At least after b5 your King is still save.
at least f5 has the tiny caveat of weakening white's center, terrible sacrifice though considering what black gets in return
No, no, this is far worse.
I don't think many openings can get a draw vs Kasparov as black. Looks like a winner.

1...f5.
1...b5!! is a double exclam (aka BOOM equals BOOM) as we all know from that April Fool's Live Sessions.
No, no, this is far worse.
Actually, Judit Polgar was able to beat Carlsen with that opening, as seen in the following game.
Votes will be counted here, new suggestions will be added if founded.
1... b5; 10 votes
1... Nh6; 0 votes
1... Na6; 0 votes
1... h6; 0 votes
1... h5; 0 votes
1... a5; 0 votes
1... a6; 0 votes
1... f6; 0 votes
1... f5; 15 votes
1... g5; 0 votes
1... Kxd8; 2 votes
Personally, I believe b5 is the worst; this idea sprang from harryz thread which can be found here -->http://www.chess.com/forum/view/chess-openings/what-is-the-worst-first-move-for-white