premature age

When a person (perferably a teen to young adult) say they are a year+ older then they really are.

Teen girl: Hey mom can i go to the college party?
Mom: No way
Teen girl: But mom im like 18!
Mom:Oh your only 17, stop having premature age!

Girl1:Hey guys lets go to the clubs!
Girl2:omg ya, im in!
Girl3:umm..unless you have a fake ID or premature age we cant get in!