To get this achievement you need to visit two locations in the mall with the "Adam the clown" costume, which is unlocked after completing chapter 2 in the story.
The two shops are located near the food court (one slightly left of the food court, one more to the right of it). For a detailed look at the locations, please watch the video below.
Be careful: According to some forum entries, this achievement is
possibly missable/glitched. If you enter the 2 shops without the costume you possibly have to start over and visit them with the costume for the first time. Personally, I can't confirm if this is true or not. Just to be on the safe side, do not visit these shops beforehand.
(video credit: DS Productions)
Hope this helps!
Any improvements? Please let me know in the comments below ;-)