Aaron,
The rind of the orange, or lemon contains oil which is flamable. Take a
lemon twist, and twist it with the rind faceing the flame, and you will get a
flash as the oil ignites. The same holds for the orange, and probably any
citrus fruit. Cut off a piece of the orange rind about the size of a silver
dollar, hold it between your thumb and first three fingers, face the skin
towards the flame and squeeze firmly and quickly. The oil will flame, and it
imparts a great flavor. Really good if you do it to Harveys Bristol cream
sherry.