grow down
When young kids think their grown. And it's obvious that their not!
Mom: I can't believe you just said that.
Daughter: Well mom, I guess I'm gettin old....
Mom : grow down, No one says that any more
Daughter: Well mom, I guess I'm gettin old....
Mom : grow down, No one says that any more
growing down
when someone grows taller and becomes worse as a person
I feel like my little brother is growing down. He used to be such a sweetheart, but since he's grown to 6'1" he's gotten three detentions.