Everyone's picking what they think they could beat, if I'm fighting something I wanna take on the best there is even though I would probably lose. I am actually psychotic like that. I don't imagine the 100 tiny horses would be nearly as challenging so I'd pick the giant duck.
I assume I'm unarmed, and we're on an open flat plain. Generally, my targets are going to be the legs, eyes, and throat. I doubt I'd be able to break the wings easily and I doubt I'd be able to break its ribs or anything through the feathers. Plus the beak would be a bitch to avoid.
I figure, given the size ratios, I'd have to wait for it to peck at me before attempting some sort of couter attack. But the length of the beak might make it too hard to hit the eyes. I guess it depends how big this duck actually is, if it's head is at the height of the horses head/shoulders then teh beak should be short enough that it trying to peck at me would bring it's face close enough for me to stab it's eye with one hands while deflecting the beak with the other. Or at least trying to deflect it, I figure the way I'd ultimately lose is getting my arm broken from being grabbed and shaken. And then there's the problem of if this duck is going to fly away like a bitch if I injure it. I'd like to assume this is some sort of psycho bushido duck who is defending it's family honour or something. But if not then the fight might be over pretty quick if I get a good hit on an eye. In which case I'd prefer to take on both the giant duck and 100 tiny horses and see how far I get with that. Win or lose, that'd be really awesome. I imagine the duck might try to fly around and land on me which would be interesting to figure out how to avoid and take advantage of.
All in all it would be a very interesting fight which could go either way and there is genuinely a part of me that's sad that I can't actually do this. Although if I could I would prefer it to somehow not be an actual duck because I'm not into hurting things just for fun or throwing my life away meaninglessly. If there was a way to do it star trek holodeck style or some sort of pocket dimension thing or something I'd be all over that.