Definately the Right Day
Some people just have a tough time remembering the accepted spellings of certain words. There are a few that I always have to think twice about too.
Occasion, for example. I usually get it right if I think first about the related word occurs which has two c's and one s.
Wednesday would be a problem if I didn't think of it as Wed-nes-day in three syllables.
I'm pretty sure that some of the misspellings you see online these days are made by people who just don't know the difference between words like then and than, your and you're and ur, and so on.
January 22 is the one day of the year on which you're permitted to misspell definately. And that's the way it's usually correctly misspelled - substituting an a for the second i.
This is another word I might have trouble with, if I didn't consider that the word finite is its root. I know there's no such word as finate.
So feel free on Misspell Definitely Day to spell it however you like. I guess it's a bit of an oxymoron that the official name for this special day doesn't (and can't and shouldn't) misspell the word in question.
You may want to avoid quoting Rain Man today. Actually, definately.