A somewhat condescending phrase used when responding to an often ridiculous, silly, or funny statement. It is used to denote to the person who said the statement and can probably be likened to saying "Tsk, tsk" or "Oh brother."
Often a person will shake their head, laugh, or point when saying it.
Moses: LALALA I LOVE SCHOOL!!!!
Tina: *Shakes her head and laughs* This kid......