The funny part is - if you are against donating your organs (for whatever reason) you should let someone in your family know. If you have a healthcare proxy (and we all should) it should be that person that you tell.
The organ donor network is notified of all deaths in many hospitals.
If the person who dies meets the criteria for organ donation - that family will be contacted. If they don't know your wishes - you may be an organ donor even if your against it.
It is amazing the parts of the body that are harvested - right down to the skin.