"I need to give you some reflux"

Today, Isaac and I were playing with his dress up box. He has some play doctor tools and had already checked my blood pressure and heart beat, when he excitedly exclaims..."Mommy, I need to give you some reflux" Huh?! He turns around grabs a hammer from his tool bench and starts "tapping" me on the knee. "Ouch, what are you doing Isaac?" "You know.... you need to make your knee jump, silly Mama" Reflex, not reflux!!