Once adrian has arrived in your appartment and has encouraged milo to find tracy's laptop, you are allowed to enter the bedroom.
To get the achievement simply click under the bed to find one of tracy's dildos.

I finally have this achievement, You find nothing interesting by completing it, Just a line of dialogue.

In the hallway at the start of the game, continue scrolling along just slightly past the loud neighbours.
Here look at the cone of light coming from the ceiling, the secret spot is an insignificant pixel near the top, click it and be disappointed!