I’ve run into people using various phrases that they have no idea how to actually spell them. I think they hear certain phrases, and then make a guess on how to spell/pronounce them in an effort to sound erudite.
Examples:
“wah lah”, a bastardization of voilà
“re-coop”, for recoup
Any others?
my most recent favorite?
Beacon call. As in, “I don’t live at your every beacon call”.
How do you pronounce recoup?
I’ve said Wal-lah as a joke, but I know folks who think it’s the correct term.
The funniest I ever heard was a guy being interviewed on the radio. He wanted to say paradigm, but he pronounced it “puh-RID-i-gum” - at least it was used correctly in context.
I think most folks have seen/heard “pre-Madonna” for “prima donna”
“for all intensive purposes” for “for all intents and purposes”
“taking [something] for granite”
This thread makes me want to post that ASCII of the guy burying his head in his hand in shame.
“Try and do” xxx. That drives me nuts. It’s “try to do” xxx. Just from a logical standpoint, why try if you know it its going to be done?
Also: what’s wrong with re-coop?
Back in 8th grade my teacher was telling me how one of my friends was talking about his “point of you” instead of his “point of view”
I literally learned in my junior year of college that puffy paint was called such. For my entire life I was calling it “puppy paint”. That’s not exactly what you mean, but it fits enough
Sorry, but, what the hell is “puffy paint?”
While it’s not particularly egregious, said person doesn’t know how to spell “recoup”, and instead attempts to spell it based on phonetics.
I like the “pre Madonna”/primadonna example; keep 'em coming!
Using “of” instead of “have” drives me crazy. As in “would of” instead of “would have,” or more likely “would’ve.”
When I was teaching freshman English at a university about ten years ago, one of my colleagues’ students wrote that someone was “not the fastest alp in the herd.”
For those of you wondering about “re-coop,” it’s because the OP specified expressions that people know (approximately) in speech, but have no idea what they look like on paper. Recoup is pronounced “re-coop,” but you shouldn’t spell it that way.
This doesn’t really count as a phrase, but I’ve heard a few people say “acrost” as in “The store is acrost the street.” 
I’ve also heard people pronounce hyperbole as “hyper-bowl”.
I have seen “recoup” spelled as “recupe”, presumably the individual thought of the similar word “recuperate” and spelled it accordingly.
Also, “esposed to” instead of “supposed to.” “Parabola” pronounced as “pair o’ bola.” And I have heard “caveat” pronounced “kuh-veet” about 100 bajillion times, which is 100 bajillion times too many.
I could care less about this thread. 
“Try and . . .” makes me feel shouty. I don’t think it’s a misused phrase so much as horrible grammar, but whatever. Unless “try and” is immediately followed by “try again” the speaker should be promptly drawn and quartered.
Oh, it’s ree-coo. The P is silent. I hope.
Sorry, forgot to add this to my last post.
This seems to be an old and accepted (albeit informal/colloquial and sometimes idiomatic) usage.
ETA:
No. It is definitely /rI’ku: p/. OED agrees with this, at least.
“Kitten caboodle” here on the boards recently. I don’t have the 5 minutes to search it out.
Slight hijack:
I still don’t like the term, “fi’in’ to” (fixing to) instead of “about to…” or “will soon do…”.
My ex used to pronounce hideous as hide-us.
OP here. To clarify the topic: Speaker for the Dead said it best.