Looking on Spotify led me to consider which good songs about unusual topics achieved unlikely success. This has been asked before, but not recently, and not based on popularity.
I was originally thinking of Tom Waits and the huge collection of instruments he has occasionally used. But that in itself does not make a song that unusual, maybe.
I thought of What Does The Fox Say? But then Googled this list, which I cannot better. I think you can, though.
“My Ding-a-Ling” was Chuck Berry’s only #1 hit in the US. The Father of Rock & Roll only hit it big with a really puerile novelty song.
“Convoy” (at #10 on the list in the OP’s article) was a #1 hit on the Billboard Hot 100 chart in 1975 (and spent 6 weeks at #1 on the country chart).
It’s largely a spoken-word “song” (with a chorus sung by some background singers), using a trucker character who had been developed as a spokesperson for a series of ads for a bread company. It is about a group of truckers who drive, coast-to-coast, at a high rate of speed, in defiance of the 55mph speed limit, while conversing with one another on their citizen-band radios.
I actually owned the Nervous Norvus song “Transfusion” in the OP.
And, three that are not on the OP list, also from the 1970s/early 1980s:
“Star Wars Theme/Cantina Band,” a disco-fied version of various themes from the Star Wars soundtrack (along with some sound effects), hit #1 for two weeks on the Billboard Hot 100 in the fall of 1977, and was also a top-ten hit in numerous other countries; it took advantage of the massive interest in Star Wars, as well as the popularity of disco. (For what it’s worth, a “single” version of the actual orchestral theme from Star Wars was also a top 10 hit in the U.S.)
“A Fifth of Beethoven,” a disco version of Beethoven’s Fifth Symphony, reached #1 on the U.S. chart in 1976.
Finally, “Hooked on Classics,” a medley of various well-known orchestral pieces, backed with a disco beat, reached #10 on the Billboard Hot 100 in 1981.
Dominique - Top of the charts in French
Oh, and speaking of “Convoy,” and CB radios:
Red Sovine recorded a “song,” “Teddy Bear,” in 1976; I put “song” in quotes because Sovine didn’t sing at all – he just told a story over some backing music. Anyway, the song is about a sick little boy, whose late father was a trucker, and who keeps himself company by befriending truckers over his CB radio (his CB “handle” is “Teddy Bear”).
It’s maudlin and weepy, but because trucking and CB radios was such a part of the U.S. culture at that moment, it was a #1 country hit, as well as making it to #40 on the pop chart; it also spawned two unrelated sequels (one by Sovine).
“Wreck of the Edmund Fitzgerald” seems a really unlikely topic for a popular song.
Not the US, but Frank Zappa’s “Bobby Brown Goes Down” was a massive hit in continental Europe, his biggest (and only). I don’t know how it happened and if even for second language English speakers the obscenities were too obscure, but it got regular airplay at least at German radio stations which I can attest. Only the DJ of my favorite radio show, “Mel Sondock’s Hitparade” refused to play it because it was to dirty for him (which of course made me only more curious). At the time I was 11 and only had had a year of English at school, but there was a magazine called “Star Songs” or something alike that had the lyrics of most contemporary hits. When I read the lyrics there, I knew that it was dirty, and I knew what the dirty words were, but not the actual meanings. Hey, it was a nice doo-wop song!
Here’s the song. Caution, very much NSFW:
Hard to believe the list left off Fire by The Crazy World of Arthur Brown, which in 1968 reached #1 in the U.K. and #2 in the U.S.
“Hocus Pocus,” by the Dutch band Focus, features truly unusual vocals: all of the vocals are nonsense words (yodeling, scat-singing, and a style of vocals called “eefing”).
It was a #9 hit in the U.S. in 1973.
The treacly, if beautiful, French instrumental “Love Is Blue” by Paul Mauriat’s orchestra topped the chart for four weeks in 1968.
Two songs that always make the worst song ever lists spent nine weeks at the top in 1968, Herb Albert’s “This Guy’s in Love with You,” four, and Bobby Goldsboro’s “Honey” for five.
Jeannie C. Riley’s country song “Harper Valley P.T.A” also hit the top that year and that was both unlikely and unusual. Classic rock, my left eyeball.
Other number ones from the “rock” 60s. “Something Stupid” a love song sung between father and daughter Frank and Nancy Sinatra in 1967. David Rose’s “The Stripper” and Bobby Boris Pickett’s “Monster Mash” in 1962. The Ballad of the Green Berets" by Barry Sadler and “Winchester Cathedral” by the New Vaudevill Band, both in 1966. Kyu Sakamoto and the Japanese-language “Sukiyaki” in 1963. And closing out the decade in 1969 for an unbelievable six weeks was “In the Year 2525” by Zager and Evans.
All number ones. No matter how weird you think the 60s were, they were even weirder.
I always thought Toni Basil’s Hey Mickey sounded more like a cheer than a song…but it’s definitely an enjoyable earworm.
I thought Vangelis’ Chariots of Fire was a bit unusual for a “Top 40” hit.
Perhaps not a popular song, but certainly a track on one of the most popular albums of all time is George Harrison’s Within You Without You. Pretty unusually for the time.
And, of course Revolution #9 from the Beatles White album is just too odd to include.
How about ‘The Lords Prayer’? Sung by a nun, of course.
Reached No 4 on the US charts apparently, No 1 in Australia.
How about MacArthur park? Seven minutes of a rambling song about a cake I mean about romance “sung” by an actor. Very polarizing (I like it)
Shaving Cream, a song that just was an excuse to almost say “shit” on a popular record.
Popcorn, “by” Hot Butter. An entirely synthesized instrumental single emulating the feel of watching corn pop, done by session musicians,
Wild Thing by Senator Bobby, a version of the song “by” RFK. It faded from popularity after his assassination. “You, you make my, uh, haaart sing” “Very good, Senator!”
Life Is A Rock (But the Radio Rolled Me). A breathless speed recitation of popular songs, music stars and pop culture trends.
I vote for Gimme Dat Ding. Don’t know how high it climbed on the charts, though.
#9 on the U.S. Billboard Hot 100; was also a top 10 song in Ireland, Canada, the U.K., the Netherlands, and New Zealand. 
Good ones. The Green Berets one was the first one to pop into my mind, but America was way more conservative back in the day, so it wasn’t a shocker, though it was a strange one to hear on a radio stations on which it was preceded by a Rolling Stones ditty, followed by something from the Byrds, like Turn! Turn! Turn!.