You have to try extra hard to beat the bad moves so that you don't get embarrased. I think I handle unorthodox openings pretty well. Out of all 4 times I faced 1...Nc6 against e4 I won every time with 2 d4 e5 3 dxe5 Nxe5 4 Nf3.
The unsoundest opening that you've ever lost a game to

Elubas wrote: "2...Ng8 is not unsound. It's fine. I'm suprised someone like you would think it is.
In a 1 minute game I lost as black to 1 g4 d5 2 g5 Qxg5 3 a3 e5 4 d4 exd4 5 Bxg5, and resigned."
You may have got your move order wrong -- 2... Qxg5 is not legal :-)

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
I pray you cannot beat me, if you can, I may have to commit seppuku myself.

asds255 wrote: "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 might go instead with the Reverse Cobblepot: 1.f4 e5 2.g4
If your opponent doesn't see that they can mate on the move, and instead "just" take the free pawn with 2... exf4 then you are obliged to play for the win.

The Reverse Cobblepot is also known as the Bissbort Gambit after Julian Bissbort who successfully used it to secure a draw at the Wurttemburg Under 16 championships in 2001. His opponent Johannes Becker is reported to have said "I was just so stunned by Bissbort's audacity that I simply had to offer him a draw. It seemed like the only decent thing to do."
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
I scored 100% this season with the Morra vs opponents averaging around 1900. It can't be so unsound :)
Also the Fried Liver definitely isn't unsound. It's at least equal for White.
The unsoundest opening I've WON with is the Saragossa Opening, 1. c3 (followed by 2. d3 regardless of Black's reply). What makes the story good is that the player I beat with it was Jude Acers, US Master, in a game with a $10 bet on it in Jackson Square, New Orleans. This was 30 years ago when Jude was in his prime. Last year he was the highest finishing American at the World Senior Open. Subsequently I used the same opening to gain a draw in a tournament game with USCF Master Neal Harris. There is something about the sight of such a weak opening that makes masters feel they should be able to crush it, and this impulse can be used against them. But while weak and defensive, the opening is not, perhaps, actually unsound. If White is determined to play defense from the start, it has certain assets.

First things first, Damiano Defense is one of the weakest openings, and I jump for joy when I meet it. Unfortunately before I knew the correct way to break it a part I have lost to it, and I've played it a few times.
In the right hands Bird and Halloween are completely sound, the latter often lethal.

In college, I may have lost a game or two to what we called the Meatball.
1.e4 f5 2.exf5 Kf7
I think its
Fred Defense
Reverse Tumbleweed
In my last tournament I got spanked by the move 1...b5 after my Nf3.
Basically he played a bunch of pawn moves, I decided his opening was crap and attempted to refute it within 10 moves...I ended up with nothing but a missing rook and soon resigned. Life isn't fair.