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The magician displays an ordinary black bag to the audience. Reaching inside he discovers the bag is empty. The bag is turned inside out revealing the inside (now the outside) is red in color.
The bag is once again turned inside out revealing a white bag. This is repeated revealing a yellow bag, then a green bag. The green bag has a zipper, and this is opened and inside is the item the magician was looking for! Easy to do! A baffling comedy effect.