An American named Satoshi Kanazawa blogs at the site Big Think about the need for a word that means an anti-shibboleth – meaning, I guess, more concisely than the term "anti-shibboleth" conveys. Rather than trying to explain, go ahead and read his article. To understand, you need to know what shibboleth means, too.
He proposes the word "frisco" as the new term for "anti-shibboleth." As a born and raised Northern Californian, I understand his suggestion completely, and I like the repurposing of the word. So, whenever you need to say "anti-shibboleth" – and, c'mon, I know you say it often! – say "frisco" instead. I hope his terminological innovation catches on.