I don’t think it was intentional, but Shatner’s rendition of “Rocket Man” sure does it for me.
Ditto for Stewie’s version:
I always want More Cow Bell nowadays.
I was never a Michael Jackson or Madonna fan so whenever I hear certain songs of their’s I’m expecting the words from the Weird Al parodies.
Never understood why Englebert Humperdink didn’t get the gears a bit more, like Please Release Me.
Surely Quando Quando Quando has been riffed on somewhere.
I believe Suzanne Vega has recorded Condo Condo Condo.
So at least one professional riff.
Some classical music starts me singing along, such as Ponchielli’s “Dance of the Hours” vs Allan Sherman’s “Hello Muddah, Hello Faddah”.
or Bizet’s “Toreadors” from the opera “Carmen”:
“Oh Theodora, don’t spit on the floor-a, use the cuspidor-a, that’s what it’s a-for-a”.
If you lived in the Washington DC area between 1982 and 1990 (as I did), chances are you were exposed to the Greaseman radio program. Doug “Greaseman” Tracht is the morning DJ who was hired to replace Howard Stern when he was fired from his DC gig. He did something called “The Tuna Fish Song” which was sung to the tune of Mozart’s “Rondo alla Turca.” Sadly, I’m more familiar with the Grease’s version than any other, and I’ve seen Amadeus on film and stage. And most of my DC-area generational peers are likely the same.
Greaseman was fired twice from the station, DC-101, for some ill-considered jokes about Black people. He briefly worked at a rival station and was fired from there, too. Not sure what he’s up to these days.
PDQ Bach (Peter Shikele) ruined Mozart’s Eine Kleine Nachtmusik for me.
And I’ll second Michael Jackson (Bad, especially), thanks to Weird Al.
if it doesn’t have to be a professional parody. My friend and I came up with a parody for part of Billy Don’t Be a Hero.
The soldier blues were trapped in a toilet
The water raging all around
The sergeant cried, We’ve got to hang on, boys!
We’ve got to hold this piece of poop (we were good boys)
I need a volunteer to ride down
And bring us back some excrement
Gangsters paradise. Then Weird Al’s Amish paradise goes through my head rest of the day.
Every time I hear Beach Boys “Kokomo” my (sick?) mind hears the lyrics of Bob & Tom’s “Camel Toe”.
There was a guy from Cleveland on my floor in the dorm back in college, who had a tape of a parody of Gary Numan’s “Cars” that some local DJ had done. Forty years later, I still can’t hear that music without the lyrics to “Bars” popping into my head.
Not strictly parodies, but Rachmaninoff was so schmaltzy in his own right that Eric Carman’s Never Gonna Fall in Love Again and All By Myself, and Billy Wilder’s Seven Year Itch “It shakes me! It quakes me! It makes me feel goose-pimply all over!” put him were he really lives in the popular imagination.
Definitely “King of Pain” by The Police. The lyrics of Weird Al’s “King of Suede” overwhelm me whenever I hear it. I have to change the station of FF through it.
Kill the wabbit! Kill the wabbit!
I love Survivor’s “The Eye of the Tiger”. But Weird Al’s “The Rye or the Kaiser” is easier to remember.
The William Tell Overture probably ought to be mentioned. It is of course the theme to The Lone Ranger.
For me, it’s “Beat It”/“Eat It.”
Also, when I hear Escape Club’s “Wild, Wild West,” my brain wants to substitute the parody lyrics from “Adam West.”
“There’s a gabardine suit on sale today…it’s 30% off from yesterday…” 
“Weird” Al songs I think of before I think of the original:
White and Nerdy - I had never heard of Ridin’ Dirty and Al’s version is much better and smarter.
Amish Paradise - Oh, I know Coolio’s song. I can not help, however, singing Amish Paradise when I heard that opening beat.
There are others that are close(Fat instead of Bad), but those two above are immediate for me. In fact, White and Nerdy seems like a much more well known song than Ridin’ Dirty, but that may be the people I know.
I can’t hear “Rock Me, Amadeus” without thinking Eat me, I’m a danish.
