Sentence:  It's particularly effective given that there's really no comeback to it: in calling someone a <WSD>snowflake</WSD>, you are not just shutting down their opinion, but telling them off for being offended that you are doing so. 
Meaning of the word marked with <WSD> tags:  Someone who believes they are as unique and special as a snowflake; someone hypersensitive to insult or offense, especially a young person with politically correct sensibilities.