As a native speaker of English living in a foreign-language environment, one comes to have some compassion for those who would like to learn English or improve the English they have (because everyone has a little, whether they admit it or not), but find themselves frustrated by the difficulties of the language, e.g. elastic vowels, phrasal verbs, an immense vocabulary, etc.
There are in circulation various pieces of verse that point out some of the eccentricities of the English language, making light and fun of them for the amusement of English speakers and the consolation of those who would like to join them.
One of these that I have seen a couple of times ends with a quip that wonders why, if one's father is 'pop,' why isn't one's mother 'mop'? Now I have to object to this, not the least because it doesn't make any sense--mom might be mop only if dad were fop, which, if he ever was, one might hope he was no longer by the time he got to be one's father--but mostly because, as I once learned, there, in fact, are mothers who are 'mop.'
I'll explain how I came to be aware of this.
Once upon a time there was a priest, a pastor of a parish, who liked to run grand penance services during the privileged seasons, como Dios manda. While planning one of these services late one Lent, he called a priest whom he had found willing to help him in the past, a priest who happened to be your humble blogger.
Unfortunately, it was that time of Lent when things start to get stressful on the way to the Paschal Triduum, I was already getting tired, and given the thought of the late night that this ministry would surely be, I was hesitant.
The priest immediately turned on that unctuous cocktail of charm and guilt that one finds from time to time among the clergy.
They love you as a confessor, Charles. I wouldn't hesitate to send anyone to you for confession. I would send my own mother to you to go to confession...my own mother!
Do you know what that means, Charles? You are fit to hear the confessions of a mop!
Upon asking for explanation I learned that the word I had heard as 'mop' was really 'MOP,' which stood for 'Mother Of [a] Priest.' And apparently hearing their confessions is some kind of special privilege or like the black belt of hearing confessions or something.
I didn't ask what might seem like the obvious question, why 'mother of a priest' might not just as well be 'MOAP,' pronounced like mope, because anyone with any experience in the matter knows that one does not find the mothers of priests moping, at least not when they are about their role as MOPs.
Therefore, since every priest, even the Lord Jesus himself, has a mother, the only dubium being Melchizidek (cf. Hebrews 7:3) who is perhaps the exception that confirms the existence of the rule, contrary to the fun little verse, there are plenty of mothers out there who are called mop.