After you get so far in the story, just after you get the ' not in Kansas anymore' achievement just to avoid spoilers, you will get access to red phone booths which allow you to take joy, save the game and then go into one of these phone boxes 3 times to overdose on joy, you will know when this happens as when you come out of the phonebox you will start coughing butterflies, then run to the nearest people around you and do anything to annoy them, let them kill you and as long as when they kill you, you are still overdosed you will get the achievement
If you prefer a video Guide
Credit for the video goes to 'A Drunkfish x'