It's one thing to be a fake fortune teller. It's quite another to practice your charlatanry on the stupidest, most gullible man alive, aka Lord Arthur Savile. Dumb as a post, dumber than roadkill, this inbred aristocrat, on being told he is fated to be a murderer, is so horrified that he loses the single brain cell he has and, instead of refusing to murder (like a sane person would), he tries to get the nasty business over with as quickly and painlessly as possible. There's a small twist at the end, and it is funny, but mostly it's funny because it's so hard to believe that Lord Arthur can walk and scheme at the same time. (He can't, of course, his schemes all go badly, but he does try.)