bubbleheaded
bub·ble·head
(bŭb′əl-hĕd′)n.
A foolish or empty-headed person: "He presents antiwar protesters ... as bubbleheads who didn't even know where Southeast Asia was" (Frank Rich).
bub′ble·head′ed adj.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
bubblehead
(ˈbʌbəlˌhɛd)n
informal a frivolous person
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014