While there was a time when the slip dress was considered strictly bedroom — a hidden inner layer normally associated with curlers and fuzzy slippers — the lingerie -inspired frock has shed its pajama moniker to become a bona fide stand-alone dress. The slinky, Victoria's Secret catalog-bound number of the '90s has evolved past adult sleepover jammies . In fact, it's even evolved beyond the Céline and Saint Laurent chemises that kickstarted the trend just two years ago.