There's a reason why our bodies can't generally handle drinking a cup of boiling hot water until it has had a chance to cool down. Drinks hotter than 65 degrees Celsius or 149 degrees Fahrenheit could increase your risk of contracting esophageal cancer in the future. If you have one little accident and take a sip of a too hot drink, you've got nothing to worry about - t's only a danger if you regularly drink very hot beverages.
While most restaurants in North America won't serve scalding hot drinks, it's something to pay attention to if you make your own hot coffee or tea at home. It's also something to consider if you're a regular drinker of the South American tea known as mate, which is traditionally prepared and served at extremely hot temperatures.