Unbelievably ridiculous. The phrase has a double meaning intended, in that you can tell someone what they are telling you to do is unbelievably ridiculous without risking their direct anger because you didn't exactly say "unbelievably ridiculous". If they ask you what it means because they perceive insult, you can say it means "not ridiculous" as in "That's not ridiculous," which they can then interpret as a statement of compliance with their directive. It can be believed by the: principal, teacher, boss who gave you the task, while your friends know you are criticizing a superior whom you must do what they tell you, but have a habit of telling you to do things that are unbelievably ridiculous.
It must be used in an agreeable tone.
"You want me to take the bottom bits out of the deep fryer and mix it into the soup after separating out the black parts by hand and throwing them away first?"
"Yeah, we can squeeze three more bowls of profit out of this batch that way without having to spend more money on ingredients. The customers say the soup is really filling when we do that."