he was talking about your incredible lack of ability to spell
*Your *cat's **Cat's (because its a proper noun in this case) *nightfall
The apostrophe (') indicates that the "Cat is" shortened to "Cats" this implies that either multiple cats are about to assault OP, or that the cat owns the idea of OP having their ass kicked, "Cat's" is the proper use of the apostrophe, I get that English is hard, but do we really need to give you 2nd grade grammar lessons?