Well, he already seems to have forgotten about that. Just yesterday (6 February) he opted to share an adorable photo of himself with his nine-month-old baby, who was of course named with the unusual moniker of X Æ A-12 - or X Æ A-Xii, as it was changed to (more on that in a bit).
Alongside the picture, which shows the baby tugging on his dad's shirt as he speaks on the phone, the Tesla founder wrote: "The Second Last Kingdom."
His post has already received nearly half a million likes, 17,000 retweets and plenty of comments from the online community.
"Looks so much like you," wrote one follower, while another simply said: "Adorable."
There was also a tonne of stocks/crypto-related replies, including one who joked: "We need to make a new cryptocurrency and name it X Æ A-12." Pretty cool idea if you ask me.
The SpaceX CEO welcomed his uniquely-named son to the world in May, alongside the infant's mum, singer Grimes.
Although the world was taken by surprise when the pair got together, somehow their relationship makes perfect sense.
They're probably the only couple who would come up with a name as out there as Æ A-12, for a start.
The moniker caused quite a stir when it was revealed last year, leading the pair to explain where it came from.
You can see Grimes' description in the tweet below:
•X, the unknown variable ⚔️
•Æ, my elven spelling of Ai (love &/or Artificial intelligence)
•A-12 = precursor to SR-17 (our favorite aircraft). No weapons, no defenses, just speed. Great in battle, but non-violent
(A=Archangel, my favorite song)
(⚔️:mouse2: metal rat)
- ࿎ (@Grimezsz) May 6, 2020
While in an interview with Joe Rogan, Musk also explained: "First of all, my partner is the one who, mostly, actually came up with the name. I mean it's just X, the letter X.
"And then the Æ is, like, pronounced 'ash'... yeah... and then A-12 is my contribution."
Although when it came to registering the little fella they had to make a hasty change in keeping with Californian law.
According to state legislation, people cannot have Indo-Arabic numerals in their names, so the singer and the billionaire couple changed it to... X Æ A-Xii.
Grimes confirmed the news on her Instagram account after a fan asked: "Did you change the baby name because of Californian laws? What is the baby's new name?"
The Canadian pop star, real name Claire Boucher, replied: "X Æ A-Xii."
Well, that's settled that.
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