Someone who gains sudden fame for something nice and positive, only to soon after be revealed as a deeply flawed character with terrible opinions and/or a shady past, often involving corrosive social/political ideologies, which quickly tarnishes their fame and the good will people momentarily had towards them.
"The whole internet loves Milkshake Duck, a lovely duck that drinks milkshakes! *5 seconds later* We regret to inform you the duck is racist" -@pixelatedboat via Twitter
What looks like a duck, swims like a duck, and quacks like a duck, is a duck (probably).
Where duck is used as a metaphor for something usually totally unrelated to ducks.
"Hey, is that guy a republican?"
"Well, if it looks like a duck, swims like a duck, and quacks like a duck, it's probably a duck."
When a bitch is trying you and you need them to "fuck a duck".
It means "fuck off", but with a little bit of humor.
When you cant stand an annoying person and just want them to leave.
Go fuck a duck Jerry i am tired of dealing with you right now.