The age where an American can:
1. Legally buy pornography
2. Legally buy cigarettes
3. Legally gamble in Indian Casinos
4. Legally be concidered an adult
5. Be tried as an adult in a court of law
6. Be drafted for a war they don't believe in
... but still cannot buy alcohol.

Intelligence agency term for "psychological operation". A government or corporate-sponsored operation, usually taking the form of a "terrorist attack" or "crazed gunman on a spree", with the intent of panicking the public into demanding more police and laws inhibiting freedom. Psyops are usually carried out by drugging a civilian or group of civilians with aggression-promoting drugs, psyching them up, arming them, and sending them out to commit mayhem. Government-sponsored terrorism. See also blackshirts, conspiracy

The age you're waiting for your girlfriend to turn.

The age at which your dick stops growing

You're old enough to know better, but young enough to not care

The number eighteen is often said on intercoms in grocery stores late at night as a code to let store workers know that there is a pretty girl close by. The one represents one girl and the 8 represents the curves on her body.

The age which you are first considered a human being at. Any age below 18 is highly discriminated against almost everywhere in the world and you are not yet human in the eyes of almost everyone. People under the age of 18 are legally allowed to be, with the exception of being murdered or tortured, treated exactly like slaves of the 1800's by slave owners, called "adults, parents, or gardians" for obvious reasons.