I am going to = I’ma
all of the time = all’d time
I picked those up from characters I liked in various movies and TV shows. Although I guess that’s slurred speech moreso than it is mispronunciations.
I have been known to say character with a ch rather than a hard c too.
I do couple of the things other people do, like skissors and musckles and such. I also say uncley instead of uncle. I don’t know why!
And my husband and I put random "en"s into some words, like sun-en-glasses, and our favorite TV show X-en-Files. And yes, we always say them that way. And "ma"s too, like heli-ma-copter.
Someone else mentioned that great French store tar-ZHAY, but there is also hoo-TAIRS, since my town got a Hooters last year. On the other hand, we do pronounce the t in Home Depot and Office Depot. And we always say Wallymart.
I can also be really bad at exaggerating my accent, which is a bit hick and long on the i’s. It’s one of those things that started as a joke, but now I can’t stop myself on certain words!
'Pacific" for 'specific, ’ and ‘ve-ha-cle’ for ‘vehicle.’ Both impressed me as a young cadet as part of the Army Creole. Cool stuff when you are a cadet.
Haste-ah man-yan-ah.
My husband and I often say yoo-bi-QUISH-ous for ubiquitous, as a joking reference to a friend’s dad. We have also been known to say poisonberries and olips instead of boysenberries and olives, because our toddler is just so darn cute.
In order to make my husband scream, I sometimes say tak-ee-era instead of taqueria, because that’s how I used to think it was pronounced, and it drives him crazy. He speaks fluent Spanish.
Just remembered another one - gour-MET, especially in a self-deprecating or tounge-in-cheek context. As in, it’s never a gourmet pizza, it’s ALWAYS gour-MET.
And the Ins key on the keyboard is the Insect key.
We say “Unkey” Winn after “Unkey Herb” on the Simpsons…
My father, holding a half-empty quart mason jar of burboun-coke: “But ossifer! I only had (holding up three fingers) two jinks!!” (not to a cop, at a party, and he drove later)
Thanks to my ruddy bastard of an ex-roommate, 9 times out of 10 when the telephone rings I’ll say “Teflon!”. I’m fairly certain that my co-workers are going to lynch me for this soon, too.
From at least one old Bugs Bunny “Stra-TEE-gee” instead of “Strategy”.
I can’t say Barbra Walters’ name without saying “Bahbwa Wawtas”. God forbid I should ever meet the woman.
An old friend of mine married a Japanese woman who passed on “Totarry” for “Totally”.
From my childhood, “Helicopter” and “Monkey” will always be “Hoptitopter” and “Gicky” respectively.
“After answering the teflon on the hoptitopter, Bahbwa Wawtas torray reassessed her straTEEgee regarding interviewing the gicky trainer.”
When I play poker I bet, “TREE FIDDY!”
Yesternight’s an actual, if archaic word, akin to yesteryear and, of course, yesterday. Mayhap you should get a better dictionary. 
Mines are oddvious
I’ll avoid “correct” pronunciations I regard as silly, such as “im-pee-yus” for “impious”. I pronounce it “Im-PIE-us” every chance I get. Which is practically never.
Another is “primmer” for “Primer”, which all rational beings can see should be pronounced “PRY-mer”.
sometimes “perhippsile” or “perhippity” instead of perhaps.
on-yone for onion like the cajun cook, natch.
“a rubber derchie” for “arrividerci”.
Sometimes I’ll say “para-dig-em” for paradigm but if you don’t know your audience, they’ll just think you’re a retard.
Don’t forget the word that follows Y’ont to: Skweet. (Let’s go eat)
The Denver Bonkers football team.
The Denver Lugnuts basketball team.
Perzackly.
There’s a senior creative director at one of the big ad firms who, despite being a native speaker, has a grasp of English that ended somewhere around 7th grade. He insists that copy should be peppered with as many SAT words as possible, but then proceeds to score a 200 when it comes to meaning, spelling or pronunciation. It came to a head when he was describing what he wanted for a particular car ad. He was pacing around, waving his arms, searching around for the word he wanted, when a sudden inspiration struck. He whipped around to face us and said with a grin of proud achievement:
"It has to be… GRANDOYCE!
My boss and I nearly shit ourselves right there. Somehow, we managed to keep from laughing out loud, but neither of us remember much after that.
Since then, ‘grandiose’ has always been ‘grandoyce’ in our office.
“poin-sett-i-a”
“ba-log-na”
“Scra-ge-dy” (Bugs Bunny’s “strategy”)
because they annoy my mother, the english teacher.
Just remembered how someone once typed “It has a certain…GENASAQUA” at me. I don’t have a lot of occasions to use the phrase je ne sais pas, but whenever I do…Midwestern accent, one word, three syllables.
It’s kuh-niffy. 'Round my house anyway.
Similarly, sammich, animule, mazagine, Saabaru, bananana, prevert (I recall Cecil using this)…
Woostasoostasoostashire for worcestershire sauce.