to be on another planet | what ˈplanet is sb on?
( informal , humorous ) used to suggest that sb's ideas are not realistic or practical :
He thinks being a father is easy. What planet is he on?
to be on another planet | what ˈplanet is sb on?
( informal , humorous ) used to suggest that sb's ideas are not realistic or practical :
He thinks being a father is easy. What planet is he on?
Oxford Advanced Learner's English Dictionary. Оксфордский английский словарь для изучающик язык на продвинутом уровне. 2005