As in "Welcome to the First And Maybe Last Vernal Equinox Quest". We are having an over-the-top egg hunt-like event at the office, which we may never want to do again. ;)
Relating to idiosyncrasy; peculiar or individual:
Ultra-idiosyncratic from a film review by Andreas Stoehr:
The experience of Histoire(s) du cinéma is not unlike browsing YouTube—itself a form of algorithm-guided channel-surfing—except here there's an ultra-idiosyncratic auteur presence shepherding you through centuries of high and low culture.