I had a pistol in my hands. I found a PET Bottle on the ground with water. I pressed Drink All on it without putting my gun in my inventory, where I had 4 slots left. I started the drinking animation, but I didn't seem to have a bottle in my hand, so it looked like as if I was drinking thin air. The gun disappeared, but the bottles duplicated. The second one was lying on the ground, but I couldn't pick it up (fake duplicate).