Sorry about continuing the hijack, but this list is irresistible.
Swedish is post #3.
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I asked my Japanese friend who said
草 kusa, means grass or herb and is often used in place names
井 i, means well (that you get water from) and is also common in place and family names
However, putting them together is kusai which mean stinky.
香織 Kaori means a scent and is a common Japanese girl’s name.
The name would be Stinky Scent. (note the name order is reversed in Japanese.
Where does this convention/meme come from? The above quotes are just to establish that it’s a thing. I’ve seen other references to it here in the past, and I think it even shows up in an episode of The Big Bang Theory. I never came across it in my childhood or adolescence or even as a young adult and I’m wondering where and when it became a thing.
McName dates back to the 1940’s, but Namey McName is more recent.
From Cool McCool to Boaty McBoatface: An Investigationy McInvestigation
The practice of affixing “Mc” to nouns, adjectives, or verbs “to create mock names denoting a person who … is considered an exemplar or personification” goes back at least to the late 1940s, according to the OED.
But the Internet didn’t take up the “X-y McXerson” construction in earnest until 2001, according to lexicographer Ben Zimmer: “The first [Usenet] appearance of Hottie McHotterson (on rec.games.video.sony),” Zimmer writes, beat out “Fatty McFatterson, Stiffy McStifferson, Drinky McDrinkerson, Jewy McJewerson, etc.” Zimmer also notes a cornucopia of deprecative McNicknames for George W. Bush, including “Chimpy McBunnypants,” “Drinky McCokeSpoon,” and “Smirky McWarHardon.”
Hey, thanks for that. Didn’t know it goes back so far. I searched online and found nothing.
It’s an odd sensation when you notice people using an unfamiliar expression or whatever.
Ah, I didn’t know about that, either.
But I didn’t think the expression was “suddenly everywhere,” which is what your last link implies. My first exposure was probably The Big Bang Theory and I thought it odd. A few references here on the SDMB and I realized it must be a thing. That was a few years ago, and I think the next time I noticed it was in this thread.
Thanks again. 
I lived in France for a year at the turn of the century (1999-2000).
While there, I was amused to learn not only that (a) France had a silly novelty product that was absolutely a direct analog of Billy Bass, but also (b) that product’s name was “Omar l’homard¹,” which translates to “Omar the lobster.”
For the non-francophones present, “Omar l’homard” is pronounced a whole lot like an English speaker would pronounce “Omar Lowmar.”
I think the OP is primarily asking what silly idioms exist in French that are parallel with the English [foo]Mc[foo]face, if you take my meaning. I don’t speak French well enough to list a series of examples, but I’d be shocked if such idioms were absent from more than a tiny percentage of the world’s languages.
“Billy Bass” repeats consonants, while “Omar L’homard” repeats vowel sounds as well as consonants—and it rhymes with itself. The English phrase “happy camper” appeals to English speakers for many of the same reasons “Omar L’homard” rolls off the tongue in French.
Repeated vowels/consonants and rhyming are pleasing not because one speaks a particular language but because all humans like that kind of phonic wordplay—regardless of their native language. (I think this is part of the OP’s point). I’m no linguist, but I’d be shocked if most languages—including French—didn’t have idioms homologous to the English “Boaty McBoatface.”
Like I said, my French isn’t good enough to tick off examples of such idioms extemporaneously. But here’s an example that’s perhaps in the same ballpark:
CamelBak, the US-based manufacturer of backpack hydration bladders, counted bicycle racers among its earliest and most enthusiastic customers. Watching French coverage of the Tour de France in the early aughts, I heard a commentator refer to a rider’s CamelBak hydration bladder as a “dos de chameau,” which is a literal translation of “camel(’s) back.”
I was thrilled to learn that French not only preserved the repeating vowels of “CamelBak” in the French name—and “dos de chameau” even rhymes with itself² in a way that “CamelBak” does not.
I can’t fully answer the OP’s question about which French idioms roughly correspond to “Boaty McBoatface,” but I strongly suspect that similar idioms exist in most languages.
I believe there are actual linguists on this board; again, I’m not among them, so I welcome input and corrections from anyone with actual linguistic expertise.
¹ I was absolutely certain that this nugget of information was perhaps the least useful bit of trivia I have ever retained. But it’s vaguely germane to this thread, so maybe not.
² To pronounce “dos de chameau” the French way via English phonetics, say “dough duh shamoh” while rhyming “shamoh” with “whammo,” but emphasizing the second syllable instead of the first. (Bold text indicates emphasis. Yes, this is what IPA is for, but obviously, I’ve never learned it).
[Edits: SO many typos!]
The “mac” has a function in this: to me, it adds a degree of would-be seriousness which accentuates the silliness of the names surrounding it. It’s like the straight man trying to control the slapstick comics either side of him - and you just know there’ll be a custard pie or bucket of something thrown in his face.
So for French the nearest must be some sort of vaguely aristocratic particle like de/du/de la; so sticking with slangy terms for boat and face, how about “Canot de la Gueule-Canot”?