What are the instances which create humour in ‘The Luncheon’?

The lady says she never eats anything for luncheon but eats caviar, salmon, asparagus, ice cream, coffee and a peach. She lectures the narrator for eating a single mutton chop. She says she is not hungry but orders asparagus if he ‘insists’. The narrator plans to fake a pickpocketing if he is short of money. When she advises him to eat only one thing, he replies that he will eat nothing for dinner. Finally, his ‘revenge’ is that she now weighs twenty-one stone.