For most of human history, and even today, much of our individual identity is heavily tied to our familial identity.

Saying that someone’s mother is especially promiscuous is basically saying that you can’t trust any claims about what their true family tree is, or that it is that way on purpose.

The reason the insulter would use themselves as an example is because they clearly don’t have any romantic interest in her.

It’s less about it being an accomplishment for the insulter, and more about it meaning nothing at all to them. That you may end up with a half-sibling as a consequence of nothing truly significant.

It’s as if to say that your family’s constituency is so carelessly crafted that the entire reason you exist at all may be that someone offered your mom an Oreo for a handjob and she counter-offered with sex for the whole sleeve.

Dunno but I’ll let you know once I’m done banging your mom

Well, once one in an adult, it becomes a bit silly for sure. But when we're kids, our parents are often the center of, if not the entirety of, our universe.

Since it's something attacking a fundamental building block of our identity (with the obvious caveat that there's exceptions to almost everything), and allowing someone to attack that is not something you can just shrug off when you're young, it becomes something bigger than its real import.

That often lingers into adulthood, where an attack on family is an attack on the self, as a matter of principle. If you allow those attacks to stand without any response, it can be taken as permission to do the same, or worse, again.

As such, anyone wanting to get a rise out of people can typically rely on mom disses to get the job done.

Your mom's sexuality isn't the core of the attack. That's just the window dressing to the real purpose, which is saying "you are lesser than me, and can not retaliate effectively when I attempt dominance". In the case of OP, as everyone knows, their mom is a total slag to begin with. That is regardless of who OP is.

As far as sleeping with someone older: doesn't matter; had sex. This is a simple rule of life, that if one is the sort to brag about sex at all, any and all sex is worth bragging about. To wit, I bang your mum then bang your drum. Which is to say that yo mama such a ho that her vag emits hawking radiation.

In other words, what's wrong with intercourse between two consenting adults of any age? While it is true that yo mama's pussy is so old that she queef mummy dust, it does not invalidate her value as a person or sexual partner. Moreover, just because yo mama so ugly tying a pork chop around her neck couldn't get dogs to play with her, does not mean she is not worthy of a good, deep dicking.

To the contrary, women of age enough to have a child old enough to ask this very question on a forum such as this likely have had a great deal of sex, and thus is an excellent choice of partner for the discerning gentleman, lady, or other. To rephrase, yo mama such a ho that they call her Chicken Coop because cocks be going in and out all day, so she know the good tricks, and she is so old the Flintstones moved out of her vagina to a better cave where they met the Rubbles.

There is no shame in your mother. Consider: she is the first person to be in both the NFL and NBA halls of fame for most balls taken to the face. Indeed, she is considered to be the greatest wide receiver ever to take on an entire team by herself. Sadly, she could not qualify as a tight end, as she is such a ho that they used to be called jumpolines before she got on one. Her name on the halls of fame plaques is Peanutbutter because she spreads so easy.

Besides, take pride that you have earned the envy of others by being such a wonderful person that they can't throw disses at you directly, and have to throw them at your mom the way I throw her the D every night.

Believe it or not, there was a serious answer in there.

In my opinion the reason it's supposedly insulting is rooted in misogyny. A woman is the property of her male relatives. When someone sleeps with her without the permission of these relatives, he uses their property without permission, demonstrating his power over them.

I do realise that many people use this insult because it's just something you say. But I think it's worth reflecting about what it actually is you are saying.

Plutarch's biography of Cicero notes that:

Again, in a dispute with Cicero, Metellus Nepos asked repeatedly "Who is your father?" "In your case," said Cicero, "your mother has made the answer to this question rather difficult."

https://en.wikipedia.org/wiki/%22Yo_mama%22_joke

Because it makes them your daddy, like the other hundreds of xbox players that banged your mom.

It is an edgy 'your mom' joke that makes a lot of people angry. People get angry about a lot of stuff that is obviously untrue if it insults their in group like a family or social grouping. It was one of hundreds of illogical insults that took off because it gets a fairly reliable reaction.

It's just a funny comment like, "how's your wife and my kids" or "say hi to your sister for me."

I’ve always thought all mom disses were dumb af.

I didn’t run into them until I moved to a new school at 8yo where I guess they were popular and I was just like wtf are you talking about?

Do you care about your mom? If not it probably doesn’t hit like a good insult would.

People are obsessed with sex and relationships. If who you have sex with, and who others have sex with is important, then it's one way to take advantage of that to hurt your feelings.

Anything you care about can be used to insult you with: nationality, ethnicity, sexuality, relationship, status, hobby, intellect, etc.

In my friend group at work, it's a bit of absurdism because of the 5 of us, 3 of our mothers are literally dead and the other two are emotionally dead. The two emotionally dead ones - stopped talking to our coworkers when one came out as trans and the other was when he left the Mormon church.

We will substitute in the dead fathers as well, especially if it makes the joke funnier.

"Your momma's so old when she tries to hawk tuah, my dick gets dusty."

"Whatever, my mom is dust."

"My mom probably thinks Hawk Tuah is a gay pop star."

"Your dad wishes Hawk Tuah was a gay pop star."

And so forth and so on.

I've always wondered if it's worse if she was good or bad in bed...