Dunderhead

[Justin Bieber]

A person with no intelligence
Idiot,Plonker,[Pillock],Klutz
Dunce,Numskull, Blockhead, Bonehead, Lunkhead, [Hammerhead], Knucklehead,[Muttonhead], Shithead,Fuckhead

[Donald Trump]

[a stupid] or [slow-witted] [person]

[Jessica]

A fan of the show The Office on NBC. The word stems from the fictitious paper supply company [Dunder Mifflin] featured in the show.
You can be sure a [dunderhead] will be plopped down in front of a T.V. at 9/8c every Thursday night.

This particular definition, although credit shown to someone else, was started years ago by [Bobblehead] Gary, (Gary Dunn) the greatest Office fan ever.