There are 7 "worlds" in the game, each with 2 or 3 levels. Once you complete World 2's two levels and see the memory of the two kids having a pool party you "Can" get this Achievement.
I say "can" because you have to find it in the memory. While the memory plays you can move left or right to play the memory or rewind it. Keep playing through it until an object in the area shakes and makes a sound, once that happens freeze on that scene and a little box will appear and unlock the Achievement.
For this specific Achievement, you need to freeze when the drink cooler starts shaking, and you'll get he Achievement when the little box pops out. Below is a video for reference.