In the level "The Old House", there is an intruder anomaly that can spawn in the Living Room area. He'll be sitting on the couch, wearing a suit. He might also stand up. When you report him, he'll literally fly to the camera in that room and wiggle violently!
Once the report goes through, you'll have unlocked the achievement!
Keep in mind that he's random, but not that rare to come across in a game.