Hawking's Stand-Up

Alright, listen up, smarty-pants! This Stephen Hawking gag is all about wordplay, see? Hawking was, like, super famous for being a brilliant scientist who couldn't move or stand because he had a disease. So, when the joke says he can't stand, it means two things: he can't physically stand up AND he can't tolerate something... which, in this case, is standing! Because you, as a reader, are a chucklehead, you probably also have trouble standing because your brain is too big.