Question: how to make your teeth whiter in just 3 minutes?
Answer: Mix several teaspoons of baking soda with enough fresh lemon juice (or water) to make a paste.
Wipe your teeth and any extra saliva off of them with a paper towel.
Put a good amount of paste onto your toothbrush and apply.
Leave the paste on for 1 minute, then rinse, so as to avoid the acid effecting enamel.