"Boiling the frog" is a common idiom for making a negative change slowly enough that no-one reacts. It perhaps comes from the (incorrect) notion that if you add

"Boiling the frog" is a common idiom for making a negative change slowly enough that no-one reacts. It perhaps comes from the (incorrect) notion that if you add a frog to water and bring it to a boil very gradually, it won't notice.