estar en Babia

Etymology
lit. 'be in Babia". Babia is a town in the north of the province of León, Spain. Historically, the monarchs of León would holiday in the town. When asked of the whereabouts of the absent monarch, a reply would be "he is in Babia'. Over the centuries, the phrase came to mean being absent-minded.

Verb

 * 1)  to have one's head in the clouds; be absent-minded