ororosmunroe replied to your post “i can’t believe the bullying kid is the new milkshake duck like what...”
so milkshake duck has become shorthand for the phenomena when the whole internet falls in love with/rallies behind someone (usually a white person lbr) and then turns on them because turns out whoever they were rallying behind is actually a horrible person (racist/rapist/whatever the fuck ken bone was/etc)
it comes from this tweet but there is already a wikipedia entry about the fact that it is shorthand, as well as news articles etc.
it’s USUALLY used for people but can honestly be used to describe any phenomena that is “initially perceived as positive, only to soon after be revealed as deeply flawed”