Wear a long sleeve shirt. You will want to conceal the lighter the best you can. With the shirt, you can hide it in the sleeve, take it out and then put it back again.
Put your hands together. Secretly take the lighter out of your sleeve and conceal it in your right hand. Cup your left hand over your right. Hold the button down on the lighter but do not light it. Make sure your left hand is cupped tightly over your right. The gas from the lighter will go into your left hand.
Light the lighter. This step will need to be done quickly. Light the lighter into your left hand. Then immediately open your left hand and sparks will shoot out. While your audience is watching the performance, quickly place the lighter back into your sleeve.