*** Spoiler - click to reveal ***This is a pretty simple to get achievement, but it does require some luck. The simplest way to obtain it is to simply fire one shot from your starter weapon at every chest you come across. While other guns can be used, no starting weapon does enough damage to instantly destroy a chest if it's a real chest.
Alternatively, chests that are actually mimics will open their mouths after a little bit of time watching them.