From teaching preschool:
"No you cannot get your friends to help you lift the man-hole cover."
"You may NOT do that to the toilet."
From parenting:
"We don't lick the stove." (This was at our neighbor's house no less!)
"Your sister does not like your dirty socks in her face."
"Broccoli does not go in your nose."
"Toys do not go in the potty."