Why does metal taste funny when it touches your braces?

The taste of metal when braces touch it is due to Galvanic corrosion. This occurs when two different metals come into contact in the presence of an electrolyte. In the case of braces, the metals involved are the stainless steel of the braces and the saliva, which acts as the electrolyte. When these two metals come into contact, electrons flow from one metal to the other. This causes a chemical reaction that produces metal ions, which are responsible for the bitter or metallic taste. This taste is harmless and is usually only temporary, as the body slowly adapts to the presence of the braces.