Making Sister Laugh

Mackenzie is the best at making Brooklyn laugh.
But sometimes Brookie does her high pitched happy shriek and Kenzie gets so mad yelling back at her to be quiet. She yells at the baby who thinks it's a game and so the baby yells more and louder. Kenzie proceeds to get more worked up...and on and on...
Quite amusing that they are already such experts at pushing each other's buttons.