Agelet
An agelet is someone who acts dangerously young for their age. Similar to a brainlet, they will probably will not make it in the real world due to their tendency to not take anything seriously and act extremely childish in every situation. They are usually only fun to be around for brief periods of time.
Person 1: That new intern is such an agelet!
Person 2: I know! He called the people who got laid off boomers and clowns.
Person 2: I know! He called the people who got laid off boomers and clowns.