What is the X in X-mas?
"empty-headed person," 1972, from air (n.1) + head (n.). Earlier as a term in mining (mid-19c.) and as a military term based on beachhead (1950).
Stupid; silly; vapid; bubblehead, ditzy: the delightfully airbrained Mickie
A stupid or silly person; bubblehead, ditz: The airheads got in trouble on Spring Weekend