Take Your Pick
If you’ve been on the internet in the last year or two, you’ve likely find a person calling other, snowflake. Because so many people are easy to offend these days. Now, it is known that when it comes to snowflakes in nature, they are all seemingly different from each other. Now, I would say a proper antonym for snowflake would be, sheep. Since they are seen to be followers without question.
And well, to make people uncomfortable, add a crude joke.