A long time ago in a galaxy far, far away, or alternatively a few years ago on the show, it became common for listeners with relevant qualifications to the subject they were corresponding about to state such qualifications at the end of their letters/emails/texts. This was soon misappropriated by the general public to include less than relevant attainments, such as finishing positions in egg and spoon races, swimming certifications, and being a milk monitor.
This is believed to have started after a particularly classic Kermodian rant over Sex and the City during which he claimed "no one with any intelligence could like this". Those with opposing ("wrong") views wrote in with qualifications noted as evidence against the accusation of feeble-mindedness. This habit stuck, and then evolved to its current format.
Challenge: I heard Mr Mayo explain this just in the last few months on the show. It was when a few years ago when the Good Doctors were being self-deprecating about the show and they said, "No one with any intelligence/qualifications would listen to this show". This was what started people ending their correspondence with their qualifications, to prove them wrong. Then people started listing humorous qualifications as well. I listened for several years wondering why this tradition happened, and was glad to learn its origins a few months ago. I hope others will smile learning about it here.