In the late 80's we were developing some PC screen scraper programs using DOS and the C language. We had a really powerful editor called E. The version we were using at the time was probably E3. It allowed for all sorts of customization including writing your own functions and keyboard hot keys.
My mate Woody incorporated a spell checking routine, to check the spelling of comments only, not the code.
During a code inspection someone eventually noticed that all his comments contained the word "fuction". He said he'd spell checked each file so we wondered how that misspelling had made it through.
Was this a new word we'd not heard of?
It turned out that a long while ago he'd accepted the mispelling of "function" and it was now in his local addendum. So the spell checker accepted each occurrence.
If you do a Google search on fuction it now gives over 450,000 hits!
Q. Why did I think about this now?
A. I just got a php syntax error trying the same spelling.
And before you ask, I'm not using E anymore, more's the pity.
I'm using Visual Slick Edit, which keeps on suggesting that I type <param>
when I intend to type <p>