be on another planet

be (living) on another planet

slang To be oblivious to one's surroundings or act strangely. I have no idea what the professor said during today's lecture because I was on another planet the whole time. The millionaire investor always says something wacky in the board meetings—it's like he's on living another planet. You're living on another planet if you think your father and I are getting you a car for your sixteenth birthday. If you want a car, start saving your pennies!

See also: another, on, planet

Farlex Dictionary of Idioms. © 2024 Farlex, Inc, all rights reserved.

be on another ˈplanet

,

what ˈplanet is somebody on?

(spoken, humorous) used to suggest that somebody’s ideas are not realistic or practical: He can’t really think we’re going to finish the job today, can he? What planet is he on?

See also: another, on, planet

Farlex Partner Idioms Dictionary © Farlex 2017