If you think a theater kid is the most extreme breed of the "theater person species", you have not met a theater junkie.
A theater junkie is a person literally addicted to theater. If they are not in a play of some sort that moment, they don't feel exactly normal. They usually spend about an hour a day memorizing lines and the rest of it preparing for that night's rehearsal.
They give up things they want to do for the sake of rehearsal. They never miss one, no matter what happens. Even if they're sick, they go but are sent home because the director doesn't want the rest of the cast to catch it.
On their iPod or MP3 Player, you will most likely find a vast majority of showtunes on it. They tend to break into song randomly when they are reminded of a show.
They usually plan on going to college with a major in Theater, or go to an art's school for Theater. After that pursue a career, becoming a starving artist and loving every minuet of it.

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