If you blow out through the rubber in a certain way, it would make rude noises! The gas drills brought laughter to British schools during the Second World War: if you blow out through the rubber in a certain way, it would make rude noises! Drills were held every month, even though gas attacks never actually happened—a double blessing as the mask filters were erroneously made with asbestos, a material that we now know would have induced serious long-term health problems. Gas a