Robin and Cherry's wedding approaches, but first there's the small matter of Robin's stag do. Rachel is quick to point out that the idea of stags and hens is very regressive. These days, a gender-neutral hag do is much more appropriate, and what's more, as his sister, she's known him longer than anyone. She should be best man. So begins Rachel's attempt at throwing Robin and Cherry what is billed as the best hag do on earth.