Private Idaho 

To live in a utopian world of your own imagination.

The term may have been coined when Idaho and the surrounding states came into U.S. possession. The area was thought as a major growth area, so lifelong dreams could be supported there.

It was used as a song title by the B-52's in 1985. There was also a movie in 1991, loosely based on Shakespeare's play, Henry VIII.

You're living in your own private Idaho.

Private Idaho by Sian Silverhair June 10, 2004

Own private Idaho. 

This is a phrase taken directly from the 1980 dance pop song, "Your Own Private Idaho" by the outrageous party band, the B-52's.

It means "living inside an Idaho potato", or a very small space. Metaphorically, it refers to someone who is not paying attention because he is daydreaming, or under the influence, or otherwise wrapped up within his own very narrow sphere of interest or frame of reference.

Car Driver: Damn! That guy just pulled out in front of me as if I weren't here! We almost crashed!

Passenger: Yeah, he's just yakking away on his cellphone, in his own private Idaho.

Own private Idaho. by david lincoln brooks March 24, 2006