1) When an individual whom has yet to reach the age of twenty-one years old in the wonderful nation of America, attempts to "puke-and-rally", proceeds to fall asleep in the unit which contains urinal, fecal and vomitary matter, also known as a stall, this person is later confronted...while sleeping on the toilet, by a large man with a walkie talkie. This man proceeds to utilize his breathalizer unit to arrest the individual whom has blown a .09....man is now responsive.

2) When an individual flags down a police officer, assuming that it is a taxi. The individual is arrested for public intoxication. The indivual is released from custody then advances down the street and falls asleep in front of an ice cream shop. He is awarded with an underage drinking citation.

When you eat dirt for the first time and leave your family to build a shack in the woods

When you're too young to go on a freaking roller coaster.

In popular terms, it means "go get some hair on your balls first, child"

1. London designer fashion label (capitalised: UNDERAGE)
2. Someone too young to consume and purchase alcohol or cigarettes (lower-case: underage)

Under-age (not underage as in too young) but state of being under as it relates to inventory. Synonyms include shortage, dearth, under stocked, insufficiency and scarcity. Antonyms include overage.