Ok..... here goes. This is my pet peeve and it has been for a long time.
This error has crept into everyday usage and I see it everywhere. It drives me absolutely crazy, up a wall, bananas-- you name it, it's driven me there.
It's the apostrophe. The apostrophe does not signal pluralism. Ahhhh. I said it.
Two or more fans are not fan's.
Two or more horses are not horse's.
Two or more boys are NOT boy's.
Ok. Now I've said it. I feel MUCH better.