So many beginners try the Patzer Opening of bringing the bishop to c4 and queen to either f3 or h5, and going for a quick kill on f7. While I've never fallen for that trick in 4 or 5 moves, I've still lost against it later in the middlegame or endgame.
The unsoundest opening that you've ever lost a game to


If I ran across the Nakamura, I would go along this line:
1.e4 e5 2.Qh5 Nc6 3.Bc4 Qe7! 4.Nc3 Nf6
5.Qf3 Nd4 6.Qd1 Qc5 (7.d3 b4)(7.Bb3/Bd3/Be2 d5)
5.Qd1 d6!(5...Qd8 transposes into Two Knight's Defense)
6.Nd5 Nxd5
7.Bxd5 Qg5!
7.exd5 Qh4! 8.d3 Na5
and forget about using it as drawing weapon (except OTB) - not worth the risk

The Fried Liver Attack has not been proven to be definitely unsound yet, and though the results in correspondence chess are better for Black, in OTB play, esp. rapidplay, the stats are well in favor of White.
1. e4 e5 2. Qh5 is also known as the Terrorist Attack.

The most unsound opening (if you can call it that) that I've lost to (albeit in a 1-minute quick game) is 1. e4 e5 2. Bc4 Nf6 3. Bxf7??.
Guess I just can't move the pieces fast enough.

Great idea for a thread.
Here is my absolute most embarassing loss ever. Losing in 4 moves. (Not Scholars Mate)
http://www.chess.com/games/view.html?id=5125248

A friend of mine long ago used to play all kinds of crazy openings, just to screw with his opponents. It worked; he beat me several times playing 1.f3 2.Kf2.
That blasted unsound Bird's opening! 1.f4 and I used to be completely lost... nowadays I play much better against it, though I see it rarely.

1.f4 e6 2.g4 Qh4# is known as fool's mate I believe.
English GM Nigel Short claimed to have met Bobby Fischer online once years ago, and the opening he was said to be playing was 1.f3 2.Kf2. Interrobang here on chess.com enjoys playing this opening as well, and I believe he calls it the Hammerschlag opening.
The Cornstalk Defence is 1.e4 a5, is it?

In serious games that mattered, I can't remember ever losing to an unsound opening, but I've been held to a draw on the Black side of a Smith-Morra (1.e4 c5 2.d4 cxd4 3.c3). I know some people don't think it's unsound, but I sure do, and I'm always happy to play against it. - Mark
The Bird's IS NOT unsound. Think again. My most unsound loss was to 1.g4 about 25 years ago.
I'm sorry if you got the wrong meaning, now that I re-read I see I was unclear. The bird isn't unsound, just a horrible opening for beginner / early intermediate players. Of course, in my opinion the Bird is a foolish opening in it's entirety.

I'm pretty sure I have lost to every opening there is, and even a few that there isn't. So now the question is: what is the most unsound opening? I'm going to have to go with the Seppuku Gambit 1. e4 d6 2. Qg4!! (I have not lost to this though, lol)
edit: OK I have lost to it.
"The lack of a brain helps my skull think better." - oinquarki

The Fishing Pole goes 1.e4 e5 2.Nf3 Nc6 3.Bb5 Nf6 4.O-O Ng4, does it? I can't say I've ever had to face it.
The first time I ever lost on the black side of the Halloween gambit was to you Gonnosuke. Serves me right for suggesting the tournie.
I've been warned that the Smith-Morra is unsound, but I've been playing it all year as my main line against the Sicilian. I faced it as black once recently, and could only manage a draw as well. The refutation whatever it is is far from obvious.
A friend of mine long ago used to play all kinds of crazy openings, just to screw with his opponents. It worked; he beat me several times playing 1.f3 2.Kf2.
Interesting. I occasionally play the Fried Fox Defense of the Barnes Opening against players weaker than me: 1.e4 f6 2.d4 Kf7, just because the name "Fried Fox" sounds cool.
In another thread, richie_and_oprah made the comment that he hated losing to the Halloween Gambit 1.e4 e5 2.Nf3 Nc6 3.Nc3 Nf6 4.Nxe5, the Blackmar-Diemer 1.d4 d5 2.e4, the Grob 1.g4, the Fried Liver Attack 1.e4 e5 2.Nf3 Nc6 3.Bc4 Nf6 4.Ng5 d5 5.ed Nxd5 5.Nxf7, the Frankenstein-Dracula variation 1.e4 e5 2.Nc3 Nf6 3.Bc4 Nxe4 4.Qh5 Nd6 and the Englund Gambit 1.d4 e5 because they are so unsound. I've lost quite a few games playing white against the Elephant Gambit 1.e4 e5 2.Nf3 d5. What is the unsoundest opening that you've ever lost a game to?