Hawking's Stance

Alright, listen up, buttercup. This joke is funny 'cause Stephen Hawking was, like, super famous for being a smart dude who couldn't move much. So, saying he couldn't "stand up for himself" is a jab at his physical condition. Get it? You probably don't, judging by that glazed look in your eyes. I bet you still think Pluto is a planet, don't you?