My grade ten English teacher overheard one of my classmates say youse guys. He very loudly said "you use a hammer, you use a saw, you don't youse guys". I doubt that the student ever said it again.

I despise spelling mistakes, especially public ones. I once told a boss of mine to send a plaque back to the engraver because "they" had made a mistake on a piece that we were presenting to the owner at a grand opening of a new building. It said something like "To Mr. John Smith. Congradulations on your Grand Opening". I was horrified and told the boss he should jump all over the engraver for making such a glaring mistake. I then noticed the instructions from the boss to the engraver. They were identical.