have your head in the clouds

Meaning

1. 1

   to be thinking about sth that is not connected with what you are doing

2. 2

   to have ideas, plans, etc. that are not realistic

From the same entry

• a head
• bang your heads together
• be banging, your head against a brick wall
• be head and shoulders above
• bite head off
• bring to a head
• bury your head in the sand
• can't make head nor tail of
• do head in
• do standing on your head
• from head to foot
• get your head down