fuck a spider on the moon
When a person tells another person to do a thing that clearly cannot be done. Often used when a person has fucked up, but is too proud to admit it, and instead places the blame on someone else.
Employee: "But, you told me to do it..."
Boss: "Yes, well if I told you to fuck a spider on the moon, would you do it?"
Boss: "Yes, well if I told you to fuck a spider on the moon, would you do it?"