A Teens
A person who is 13 to 19, and if you say they're not teens, you're just being a dumb kid who doesn't know what they're talking about.
'They're teens, and if you say they're not, you're just being a dumb kid.'
'They're 18, and you're 12, so shut up and let them be teens.'
'You're just being a dumb kid who doesn't know what a teen is.'