:The condition of stay childish constantly.
:Kid at heart.
:Unable to grow up.
Loooks like someone is suffering from peter pan syndrome.
When someone doesn't want to grow up
The kids in Never Never Land Have PeterPan Syndrome
Anyone (especially males) born after the year 1990 who believes they shouldn't be forced to take on the role of a productive member of society. For example, someone who is in their mid-20's and still lives with their parents while working a minimum wage job and carrying $50K in student loan debt for a liberal arts degree. Those who suffer from Peter-Pan Syndrome also shy away from basic adult responsibilities such as taking out the trash, doing the dishes or going grocery shopping.
Peter Pan Syndrome applies to anyone born after 1990 who still lives with mommy and daddy, and who refuses to behave as a productive, adult member of society, hence "Peter Pan" and refusing to grow up. This phenomenon occurs almost exclusively in males born after 1990.