In "The One With All the Wedding Dresses," Monica is tasked with picking up Ross's fiancée Emily's wedding dress and can't resist trying it on when the store owner mistakes her for the bride. She continues the charade at home while doing the dishes, and then Phoebe shows up later also wearing a dress while also pregnant with the triplets she's carrying as a surrogate for her brother. When Rachel eventually shows up lamenting the woes of her love life, the scene cuts to the three of them in white dresses drinking beers on the couch.
What to wear: White prom-style dresses, DIY mesh veils, and your favourite bottle of beer.