in catch 22, why does the man punch doc daneeka when he shows him how to have correct sex with his wife?

Question

In Joseph Heller's novel Catch-22, Doc Daneeka reminisces to Yossarian about his days in private practice, and he talks about a couple who once came to him because they were unable to conceive a child. Despite the couple's claims of regular sex, the doctor discovered upon examination that the wife was still a virgin. He used plastic models to demonstrate to the couple how to have sex the "correct" way, and a few days later the husband returned and punched him in the face.

WHY???

Answer 1

Doc describes only one experience of his practice at home in the book: a young couple who are unable to proliferate. Doc asks them how they go about doing "it" to which they look at each other with ingenuous and innocent smiles. He concludes they have no idea about sex and, with the aid of two accurately scaled dolls, shows how a male and female are to make love. They thank him for his help and go away to give it a try. Later, the husband returns and, punching him in the nose cries, "What are you some kind of smart guy?"
My inference regarding the husband's remark is that he can't believe that babies are made by such a weird and ridiculous process.