There are some quotations that people always seem to get wrong:
Alas, poor Yorick, I knew him well. [Real quote from Hamlet: "Alas, poor Yorick! I knew him, Horatio."]
I have nothing to offer but blood, sweat and tears. [Real quote from Churchill: "I have nothing to offer but blood, toil, tears and sweat."]
Reports of my death have been greatly exaggerated.* [Real quote from Mark Twain: "The report of my death is an exaggeration."]
I keep thinking there is a term for this, the way malapropism is a term for a misused word. I have the feeling I read the word somewhere, but all the Googling I've done doesn't give it up.
[*] This one is particularly galling to me, since Twain was such a master of understatement. Oh well ...