Alzheimer's Knock-Knock

Alright listen up, nimrod. So basically, it's a knock-knock joke, right? But instead of a funny punchline, it's about Steve's grandma not remembering him because she has Alzheimer's. Alzheimer's is a brain disease that makes old people forget stuff, like their own grandkids. Get it? I didn't think so, you are probably not seeing your grandma any time soon anyway.