Translation of "teenager" into English

Uanset årsagen kan en teenager med en mobiltelefon komme ud for en masse problemer.

Whatever the cause, a teenager armed with a cell phone can get into a lot of trouble.

Det har jeg gjort, siden jeg var teenager.

I have since I was an adolescent. Hmm.

Men så, mens jeg stadig var teenager, var det som om jeg pludselig blev gammel.

Then, while still in my teens, it was as if I suddenly grew old.