Lightning is the atmospheric discharge of electricity, usually during thunderstorms. A bolt of lightning can travel at 60,000 m/s and can reach temperatures as high as 30,000 degrees Celsius. Lightning get so hot that when lightning strikes sand, it has the ability to fuse sand into glass.
The expression "Lightning never strikes twice (in the same place)" is similar to "Opportunity never knocks twice" in the vein of a "once in a lifetime" opportunity, i.e., something that is generally considered improbable. Lightning occurs frequently and more so in specific areas. Since various factors alter the probability of strikes at any given location, repeat lightning strikes have a very low probability (but are not impossible).
To the Greeks, lightning bolts were thrown by the very hands of Zeus, the father of all the Gods, and the principal God on Mount Olympus. In Norse legends, Thor was the God of Thunder, and lightning bolts were the sparks that flew when his mighty war-hammer hit its target, often the skull of a Frost Giant. Lightning was a symbol of power, and because it could not be predicted, it was also a symbol of the capricious nature of the Gods and the world men lived in. Because lightning often accompanies a rainstorm, lightning also was seen as a symbol of fertility, rain being a crucial element to a successful crop. Some cultures saw lightning as male, as the sun was male and the earth as female.
Lightning bolt tattoos symbolize power, strength and energy. They are often used as flourishing around a word or action.