Simon & Garfunkel sang it's all happening "At the Zoo," but it wasn't happening for Gil, who sadly, just couldn't make it, and Masters and Johnson are tasked to find out why, and put in a cure, if possible. The key, it turns out, is a woman who used to work at the zoo, and talked endearingly to Gil as prelude to his foreplay. But the talk wasn't the thing - it was her copious bosom that ignited Gil, and Virginia needs to bare hers to get Gil right again.
That's about where the humor ends. Virginia's not pleased about what she had to do, Bill is not very sympathetic, but that perfume guy is, and the result is she's drawn closer to him, and with the result that now much more than a bosom is shared, and with increasing frequency.
There was also was an anachronism is this story line - a rare kind of mistake for Masters of Sex - which occurs when Virginia observes that gorillas are almost "99%" like humans. That's based on genomic analysis - the Human Genome Project, in particular - which didn't take place until 1990-2003, and in fact the human-great ape comparison wasn't revealed until the end of the project. True, DNA itself was discovered back in the 1950s, but no one in the 1960s knew the degree of similarity between ape and human genomes.
Hey, it's tough to get things right, and the main reason I know about this is the research I did for my first novel, The Silk Code. And the error didn't really hurt the story.
What does hurt - not the story, but Bill, and is a powerful marker for potential damage - is when his son partially burns one of Bill's prized football cards. I almost don't want to see Bill's rage when he discovers that, but of course will be watching the excellent series with rapt attention.
See also Thomas Maier: Masters of Sex and Biography Come to Life ...Masters of Sex 3.1: Galley Slaves ... Masters of Sex 3.2: The Shah, the Baby, and the Book ... Masters of Sex 3.3: The Bookstore