Cabbie21
Being really pedantic, the OP not only used ‘what’ and ‘wrong’ incorrectly, but also ended with a preposition.
In speech, I tolerate anything, reluctantly, but I expect written text to be correct. Sadly, I am often disappointed.
My list is too long to write, but poor grammar annoys me more than misuse of vocabulary.
The worst offence has to be ‘ would of’ ‘ should of’ etc.
I am a retired language teacher.
Not wanting to 'outpedant' you, but isn't the word 'of' at the end of the sentence acting as a particle of the phrasal verb "to know of", rather than as a preposition?