Apostrophe's

Can someone please tell me why anyone would ever put an apostrophe before the ending S of a plural noun?  I see it all the time and just can't figure out what the thinking is behind it.  Examples:  apple's, chair's, dessert's.   


I know that almost nobody gives a rip, but if someone can explain to me the reason  for such strange apostrophe mis-use, I'd appreciate it; just FMI (For MY information.)  


That's all I want to say here right now.  Next time I'll try to write about something with a little more weight.


By the way (btw), the title of this short-but-boring post is meant as an example of what I'm writing about.


HELP!  I've got to get out of this "English Teacher" mode!