A burp, sometimes called a belch, is gas that your body needs to get rid of. When you eat or drink, you swallow air at the same time you swallow food or liquid. The air contains gases such as nitrogen and oxygen. The extra gas you ingest is forced out of the stomach, up through the esophagus, and out of the mouth as a burp. Some kids discover that drinking soda or other carbonated beverages makes them burp more, and this is because these drinks contain carbon dioxide, the gas that makes them fizzy. Sometimes eating or drinking too fast, which sends more air into the stomach, can make a person burp. The same thing happens when you drink through a straw: the straw brings extra air into your stomach, causing you to burp.