May cause death! Experts have determined that the components of a cup of coffee can be lethal in certain quantities so if you are able to knock back up to 100 cups in a row it could give you a fatal heart attack or some sort of seizure. However, consuming 100 cups of coffee is easier said than done as the actual amount of time it would take to drink 100 cups of coffee would dilute the effect and probably just keep you up all night.