Hot water bottle blowing is the deliberate inflation of a hot-water bottle by blowing. Air is breathed into the bottle until it stretches beyond its capacity and consequently explodes. It is a challenging feat of strength which is included in the Guinness World Records. The challenge is most commonly undertaken by breathing air from the mouth, though it has also been achieved by blowing through the nose. The activity presents a potential hazard for physical injury to eyes and lungs.