Had a coworker reference Alphonse and Gaston, and I’d bet big bucks he didn’t know it was from a comic strip.
I saw the Room and also the disaster artist which is a comedy about making the Room. The Room was funny like plan nine from outer space. Disaster artist was intended to be funny and it was. I almost never see people mention them.
I’d most of them, since it is almost always misquoted. The actual quote is “Badges? We ain’t got no badges. We don’t need no badges. I don’t have to show you any stinkin’ badges!”
I suspect most people are actually referencing Blazing Saddles. Which was, of course, itself referencing Treasure of the Sierra Madre.
While reading this I overheard a comment on the TV in the other room. They referenced War and Peace. That probably fits here.
A lot of people I know think Cheech and Chong originated it.
Also “One of us! One of us! One of us!” – people might know it from dozens of sources – they might think the “Simpsons” or “Buffy the Vampire Slayer,” or “Logan’s Run.” I wonder how many people know it’s ultimately from a 90-year-old movie.
What about the Hitler rant scene from Downfall that is repeatedly parodied with new subtitles?
I wonder if Al Pacino wins this thread by being referenced the most often from movies the majority of people have never seen?
Hoo-Ah!
I’m walkin here!
Say hello to my lil friend!
I’m outta order?!
That was Dustin Hoffman
I constantly see people talking casually about Netflix shows as it everyone has watched them- but of course only Netflix subscribers and likely not every single one of them either.
Only about 1 person in five gets Netflix.
Ah, see! I never saw the movie.
“They pelted us with rocks and garbage.”
This took me a couple seconds. 
It took me even longer when he just said 'an old sci-fi movie". It must have been a good ten seconds before I said “What, wait, Oooh… Sling Blade, not Blade Runner”.
The Wilhelm Scream. Once you know it you will hear it everywhere, and with almost certainty no one even here has watched the movie Distant Drums.
I actually think this is the best answer so far. Most other replies have named movies that were relatively popular at the time of their release, but this scene is from a small foreign German-language film, I’d be shocked if even 0.5% of those who know the parody have seen the film.
You lucky thing.
Speaking of Pacino, let’s not forget the “Attica, Attica, Attica” chant from Dog Day Afternoon.
I think this a case of people remembering the parody better than the original.
Like when people say Sarah Palin said “I can see Russia from my house” when it was actually Tina Fey mocking her on Saturday Night Live. (Palin actually said “They’re our next-door neighbors, and you can actually see Russia from land here in Alaska, from an island in Alaska.” which is a lot less stupid)
When the last person who remembers “Elvira Madigan” finally passes on, will we still be using its title as a nickname for that one Mozart piano concerto?