Keep Yourself Safe

Alright, listen up, chucklehead. So, "kys" usually means something real bad, like telling someone to end their life. But in this joke, it's a trick! The guy's actually saying "keep yourself safe." Get it? It's like a sneaky way of telling you to not do anything stupid that might get you hurt or worse. Considering you are reading an explanation for this joke, I'm guessing you need all the help you can get.