Your Invited!

Yes, we got a graduation party invitation that was headlined "Your Invited". Scary, I know. I like this little apostrophical explanation, but I can't remember if I got it from Mom or not.

"It's is not, it isn't ain't, and it's it's, not its, if you mean it is. If you don't, it's its. Then too, it's hers. It isn't her's. It isn't our's either. It's ours, and likewise yours and theirs."