This between the two oldest children.  

Child 2:  You should get rid of that on your chin. 

Child 1 just smiles and tugs upon the hair on said chin.  

Child 2:  It looks horrible, all overgrown and nasty.

Child 1 continues to smile.

Later, Child 1 tells me,  I'm going to continue to grow the hair on my chin.  And, when it grows long enough, I'm going to braid it.  Like one or two braids.  All the way down to my chest.