Get a banana and a needle. Make sure the needle is a little bit longer than the banana is wide, or you may lose the needle inside the banana.
Insert the needle into the seam of the banana. The seams of a banana are the lines that run from the top to the bottom of the banana. Do not stick the needle into one of the banana's flat surfaces.
Press the needle through the banana. You will want the needle to touch the other side of the banana without puncturing the opposite side of the peel. If the needle punctures the other side of the peel, pull the needle out a little bit.
Move the needle from side to side inside the peel to slice through the banana. Repeat the side to side motion until you are confident the banana is sliced.
Remove the needle from the banana. Pull the needle straight out to avoid turning the banana to mush.
Repeat steps 2 through 5 at different points along the banana's length, until you have made as many slices as you want.
Give the banana to an unsuspecting person and have them open it. The banana slices will fall out as the peel is removed.