You have to become a whore to unlock the pink room
To do that you have to have the whore/slut perk (not sure if whore perk is enough) and talk to someone in the truck stop area
Basically accepting sexual favours for money enough times will grant you the perk
You have to accept a sexual favour for money once then it becomes easier your character to accept more sexual favours
Working in the bar is the easiest way to do this cuz you will be bombarded with requests for sexual acts