Stephens Not Walking

Alright, listen up, nimrod. The joke is that Stephen Hawking, who was a brilliant scientist, couldn't walk because he had a disease called ALS. The joke is saying his name should be "Stephens not walking" instead of "Stephen Hawking" because he couldn't walk. It's a play on words, get it? You're probably too busy trying to figure out how to tie your shoes to understand this.