"my child will only eat McDonalds chicken nuggets"
really? Does your child have a car and drive themselves to McDonald's and purchase their own chicken nuggets? Oh? you drive there and buy them well! I wonder why it's all that they eat!
"my child will only poop in a diaper"
really your child goes and gets diapers from the store put them on and poops in them? try not having any diapers and taking that option away! Duh! (special needs aside)