This one got me lots of extra credit in school. I have an 8 word statement that is correct when said, but wrong if written. PM me for the answer.
I would assume it would be a sentence that ends in a preposition without an object. For example, it is quite correct to say "What did you step in?" but grammatically, you must never end in a preposition, so the correct question would remain "In what did you step?" a rather stilted verbiage that few would choose to use. Therefore, I would just add adjectives to increase the length of this to eight words, let's see....What stinking vile **** did you step in?
The long awaited answer is. "There are three too's in the english language". The way it is written is wrong, because there are not three "too's". When saying what is written, it becomes right because it includes Two, To, & Too.