Drinking Coca-Cola or any other carbonated beverage while eating Pop Rocks has no particular effect. Both Pop Rocks and Coke contain similar ingredients, including carbon dioxide, corn syrup and flavoring. Rumors of this combination of brand-name food creating a chemical reaction that causes explosions are not scientifically factual.
Pop Rocks produce a popping or sizzling sensation on the tongue due to small amounts of carbon dioxide they contain. Coca-Cola also contains this same gas. Combining two different substances that both contain carbon dioxide will do nothing more to the human stomach than produce a small amount of intestinal gas. The amount of gas is from the food and beverage themselves, and is not generated by a chemical reaction between the two. The amount of gas produced by eating normal quantities of these substances is not enough to cause a human stomach to explode.