Blaine says some introductory words about changing the consistency of metals. What is he going to do?
He then brings the quarter close to his mouth, and to the surprise of everyone around him, bites of about half of the coin! The girls start screaming, visibly shocked. How is something like this possible? That's crazy!
But Blaine isn't finished yet. He holds the half of the coin in his hand, and spits the half which is in his mouth back into place. The coin is suddenly restored, just like nothing happened to it!
How does he do it? First check out the video of Blaine performing the trick, and then read the explanation below.
This trick involves a gimmicked coin. The coin David Blaine uses consists of two parts held together by elastic bends. It can be folded so it looks like one half of the coin has dissapeared.
Blaine first secretly exchanges the real coin for the gimmicked one and then pretends he is biting it while he actually just folds it. He than shows the coin to the spectators and pretends to spit the missing piece back. As he does that, he simply lets the folded half of the coin jump back into place.
This is how a gimmicked coin looks like: