Biting the magical genie

I was making a grocery list, and Mike and Sarah were giving me their requests.  I said something like, "It must be nice to just wish for something and then when I come home from the store, it comes true.  I'm like a magical genie or something."  Sarah mumbled, "A magical genie that gets angry sometimes..." and Mike said, "Hey, don't bite the hand that feeds you!"  Sarah replied, "If I bite it, won't it just drop more food?"