I just explained what it actually is. I said "you know how you go to a website HTTPS and it's secure? Well Apple chose a couple of trusted parties that your phone inherently trusts, and those people approve a few thousand intermediate companies who do the day-to-day certificate work for end websites. One of those intermediates, rather than choosing a 200-digit random number, chose 4, no not four-digits, the number 4". And then we could laugh at some of the memes.