In the beginning of the game once you get your gun and ammo from the shooting range place, go back to your locker where you get your armor and open your locker. Inside is some pictures, books, and a cardboard box. Make sure you have at least 68 shots left(as in 17 loaded and 51 left) and shoot the box 68 times until it breaks. Right clicking might help here for faster shooting. When the box breaks open, it reveals a tiny one-eyed alien.