\" \" Liquid nitrogen can easily blister fingers and hands, and ingesting it can cause serious damage to the mouth, esophagus and stomach. In the U.S. you can buy it at a carnival or one of those mall kiosks — it's just cereal steeped in liquid nitrogen. When you pop the cereal in your mouth, the liquid nitrogen instantly freezes your saliva, making dense gray \"smoke\" pour out of your nose and mouth. Liquid nitrogen is pretty easy to come by, and the use of it in food and medicine has become pretty standard. And while not everyone who consumes liquid nitrogen is going to get hurt, uneducated consumers (like children) might because they don't know what they're dealing with.