Frisky Business (EP)

Tiffany is the first girl you come across in the game. After helping her with her cat problem, you will need to get her number and eventually invite her over for some one on one consultation services (Chapter 10 - choose to Text Tiffany when given the option). The trophy will unlock as soon as Frisk and Tiffany are done for the night.

If you are following the Roadmap, this trophy is part of Run #1. The Walkthrough for this can be found here.