What is the meaning of the 21st key?

Answer 1

If you live in the USA, reaching the age of 21 means your allowed to purchase alcohol and consume it inside bars and establishments that sell alcohol. It also means the tax department can tax your money hard and chase you around the states trying to dis-empower you away from your hard earned money. With that tax money they can resource their military forces round the world to seek profitable resources such as oil, better and cheaper drugs and to also kill off religious factions that don't fall under the umbrella of what Americans consider human. Watch out if you wear a turban or a vail.