bug-a-boo

A mythical, nocturnal creature; a hobgoblin.

The German ubu, as well as the French bibou, is also used for bug-a-boo, hobgoblin, or any other fantastical, terrific nocturnal object.

“Oh! Of all the intolerable bugaboos. Gentlemen, this is a family discu-- Oh!”

Any imagined fear or threat, or a fear presumed larger than it really is.

...a fear had come upon them, and they had a kind of bug-a-boo terror about roving gangsters.

There is the Goody-good Bug-a-boo, the Consistency Bug-a-boo, and the Bug-a-boo that Thomas Jefferson if he were living now, would never never ride in a carriage. Each of these bug-a-boos in the general mistiness and muddleheadedness of the time can be seen going about, saying "Boo! Boo!" to this democracy ...