Stephen Hawking The Hardcase

Alright listen up, buttercup. This joke is playing on the fact that Stephen Hawking, even though he was physically disabled, was a strong dude who wasn't gonna let anyone mess with him. "Hardcase" usually means someone tough. You know, like you try to be, but everyone just laughs at. It's funny because it's unexpected to think of a dude in a wheelchair as a "hardcase." Maybe you should try it sometime, tough guy.