I do know about the drowning thing. 🙁 I lost a duck that way my third year of keeping them. Now I make sure to put a cinder block in the deeper pools so that the girls have some way to keep from being pushed under too often, and I don't keep smaller girls with my two more aggro boys.
So there's a dance that boy ducks do after they've successfully had sex. It looks fairly similar whether they're on water or on land; they dip their head down with a straight neck, and zoom back and forth in a straight line with a hard turn midway through. It means "I got some booty I got some booty," and they do it after ANY successful copulation.
HOWEVER (I'm changing the names so I don't dox myself, though I'm really doxing myself just by saying this much, oh well)
I have two boys, (Roger and Jack) in one flock and one (Arthur) in the other flock, and they hate each other. Deeply. Arthur is with a single girl, and she's gorgeous. Roger and Jack line up at the fence between them, and catcall her. Arthur runs to the fence, and yells at them. This goes on for awhile, and if it escalates, Jack may do the "I got some booty" dance in the middle of it, as though claiming that he just mated with Arthur's wife, at which point Arthur loses his mind and starts banging his head against the fence, trying to go over and kill them.
And I'm sitting there, calling to the duck "Arhur, you KNOW he's lying. You were right here the whole time, you know that didn't happen." But he doesn't care, just them SAYING it happened is enough to enrage him.
Also Jack is bad at sex, and occasionally after trying for like twenty minutes and eventually getting bucked off because the girl is annoyed because she's tired of having her hair pulled while he fails and fails and fails at the angle, he'll suddenly do the dance as though he didn't fail. But I don't argue with him, because aw, poor guy.