DO NOT DO THIS ACHIEVEMENT BEFORE THE PIN-UP GOAL ACHIEVEMENT
With this achievement you have to get 12 puzzle fragments with one fragment.
1. At the beginning of chapter 2. After you gain control of Rufus, save your game.
2. Click on the puzzle fragment in Bozo's Cutter (in the top right corner, it's a small piece of square paper on the window)
3. Load the save, You'll see it's reappeared. Click on it again
Repeat steps 2 and 3 for a total of 12 times.
The problem with this achievement is that the game keeps track of what fragment you've clicked on throughout all of your saves, regardless of how old they are and whether you click new game or not, and to get the "Pin-up Goal" achievement you can only click on each fragment once. So the moment you click on the same fracture more than once, it locks you out of that achievement. Meaning you need to delete your saves in order to obtain it.
Annoying I know, but if those two are the last achievements you have to unlock, do this one last.