Newmark's Door

I've heard it said that to be an economist you must recognize the power of incentives. But to be a good economist you must anticipate how clever people will game the incentives they are given:

My son’s school was having issues with messy bathrooms so every month they reward the boys or girls with ice cream depending on whose bathrooms are cleaner and according to my son it’s become a prank war where they just fuck up each other’s bathroom.