That can happen on a site with a low bandwidth hosting plan. It's sorta like going past your minutes on a cellphone plan and can be very expensive if you don't have a stop like that when you reach your limit. A few years ago we got socked with an extra $2000 charge one month for passing the bandwidth we were allotted. That happens one time and you find out that it is a whole lot cheaper to pay more a month for a plan that has either high or unlimited bandwidth. Its also a good reason to make sure the images on your website are compressed as much as possible.
