The billionaire technology entrepreneur revealed that his son was born on May 4, aka May the Fourth Be With You, which Rogan pointed out was "the perfect day" for Musk, a Star Wars fan.
Rogan outright asked how to pronounce X Æ A-12, which garnered a laugh from Musk. "Is it a placeholder?" the podcast host inquired.
"Well, first of all, it was my partner [Grimes] who actually mostly came up with the name," Musk shared. "She's brilliant."
As for how to say the name, the Tesla founder explained, "So, it's just X, the letter x, and then the Æ is pronounced Ash."
Musk's contribution to the name is A-12, which is an ode to the Archangel 12, the "precursor to SR-71, the coolest plane ever."
So according to Musk, his son's name is X Ash Archangel Twelve. "It's great," he said proudly.
However, Grimes, real name Claire Elise Boucher, told one of her Twitter followers that "it’s just X, like the letter X, then A.I. Like how you said the letter A then I."
At 48, this is Musk's sixth child and his first with 32-year-old Grimes. "I think it's better being older and having a kid," he said. "I appreciate it more. Babies are awesome."
Earlier this week, Grimes attempted to share her newborn son's name and offer an explanation, but flubbed the part of the little one's name that Musk came up with.
The singer said that A-12 refers to an aircraft which is the "precursor to SR-17 (our favorite aircraft). No weapons, no defenses, just speed. Great in battle, but non-violent."
Musk later corrected her on Twitter, writing: "SR-71, but yes."
Grimes replied to the father of her child, "I am recovering from surgery and barely alive so may my typos b forgiven but, damnit. That was meant to be profound ?."
While neither Grimes nor Musk have confirmed where she gave birth, many fans believe she had the baby in California. As numerous media outlets have reported, if she did in fact give birth there, the name will not be accepted by the state.
In California, you are only to use the 26 letters in the alphabet for a baby name, and an apostrophe if needed. Numbers, Roman numerals, emojis, accents or other symbols are not acceptable.
Just prior to welcoming another child, Musk announced that he was getting rid of almost all of his worldly possessions.
"I'm slightly sad about it actually," he admitted to Rogan on his podcast. "I think possessions kind of weigh you down. They're kind of an attack factor. They'll say, 'Hey, billionaire, you got a lot of stuff.' Well, now I don't have the stuff. Now what are you going to do?"
Musk will be keeping a few Teslas for "research" purposes, as well as some clothes and possessions with personal importance to him. He will, however, be selling all of his homes and renting a place instead.
As for Grimes, prior to giving birth, she put her baby bump on display for Vogue Italiaand shared what it was like being pregnant amid the coronavirus pandemic.
"It is certainly very demanding to be pregnant in the middle of a pandemic. It's hard not to be able to see friends and family," Grimes admitted. "A friend of mine recently died and it was a nightmare not being able to be close to her loved ones. It won't be easy in the hospital, I don't go into details but I feel very empathetic with those who are going through this phase. And I trust what the maternity wards are doing to manage the situation, I have great respect for the work of the doctors."