Time for my pet peeve: People who, for whatever reason, use Shakespearean / King James constructions rather than using perfectly fine modern English forms, but can't get the Shakespearean forms right. There's nothing sacred about the old forms, but if you're going to go to the trouble of using them, you may as well use them in a historically accurate fashion.
For example: If thou sayest "he hast", "thou has", or "thou hath", thou shalt be flogged. Or if thou sayest "he wilt", or "thou will". And he who sayeth "an 'istoric", but droppeth not the "h", and thus sayeth "an historic", shall feel my wrath. The man who randomly doth add "eth" to the ends of words (as in "I randomethly addeth 'eth' to the endeths of wordeths") shall be most brutally slain.
There shall also be punishments for them who address more than one person as "thou". "Thou all hast abused the English language" and "At the border they will search all of thee" are forbidden sentences. One must say "Ye all have abused the English language" and "At the border they will search all of you". (Also remember that in Shakespearean English "ye" is the nominative and "you" is the accusative form of "ye". "You" is to "ye" as "me" is to "I"). I will not personally punish the man who addresseth his boss as "thou", but if his boss objecteth, I will not protect him. Remember that "thou" meaneth "you buddy", and "ye" meaneth "y'all" or "you sir".
Also a pet peeve, though not as bad as it is an error of understanding and not of trying to use something one does not know how to use, is when people interpret "wherefore art thou Romeo?" as "Where are you Romeo?". The actual meaning is closer to "What the heck did you have to be called Romeo for?"