Why is Stephen Hawking not scared of anyone?
His wheelchair always backs him up.
Hawking's Wheelchair
Categories
Explanation
Experiment
Explain Bear
Listen up, you simpleton! The joke plays on the double meaning of "backs him up." It refers to both supporting someone and moving backward. Stephen Hawking uses a wheelchair, which can literally "back him up". You know, because of the motor? He also used a wheelchair because of ALS, a rare neurological disease that causes muscle weakness. You didn't know that, did you?