The fastest way to whiten teeth without going to the dentist?

Home whitening kits. Some of the home whitening kits have the same ingredients that dentists use, just a lower concentration. Follow the recommendations on the package. Trying to use them for a longer time each day may speed up the bleaching process, but could increase the risk of discomfort from the bleaching process.
Fastest way? When someone asks me the "fastest way" the only thing that comes to mind that is a viable answer are directions from one place to another. Fastest way that is asscoiated with weight loss, muscle mass, tooth whitening, etc has an undertone of snake oil. Some things have an order where for the best result you cannot skip form a to d. Before bleaching a checkup and cleaning are THE first step.
Store Whiteners. Some of the well know manufactures have some worthwhile products that can do this. However a good dental cleaning is very useful first. You cannot whiten such things like: cavities, decalcification, etched tooth structure from acidic foods and/or bacteria, stains within the porosity of the tooth structure, fillings, crowns, and many more things that a dentist can help you identify and assist.
No good way. Dental whitening strips and whitening toothpastes may help a little, but best if teeth cleaned by your Dentist first. Custom trays made by your Dentist used with whitening gel much more effective. Best bang for your buck, ask your Dentist for help.
Whitening. One can try store-bought whitening kits. I encourage you to see a dentist prior to bleaching to make sure your teeth are sound so that complications from whitening can be avoided.
No. There are crest whitening available at the pharmacies but because of their low concentration usually wont give the optimal result. The easy and effective way is having dentist fabricate a home whitening tray that you can use at home during the day or night.