be (living) on another planet

(redirected from is on another planet)

be (living) on another planet

slang To be oblivious to one's surroundings or act strangely. Primarily heard in US. 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.
See also: another, on, planet