Green’s Dictionary of Slang

to fool, to confuse, to overcome by trickery.

1838		‘Nights At Sea’ in Bentley’s Misc. Apr. 595: I felt quite conflustercated when I heard him name the leftenant’s name.
1890-1904		Farmer & Henley Sl. & Its Analogues.
1915		Weekly Times Record (Valley City, MD) 1 July 2/3: We have got our corporations all conflummoxed, out of fix.
1941		Story Mag. 18 63/1: ‘Now don’t conflummox me,’ Sam groaned. ‘Tha’s had a comfortable week — now it’s ma turn. Go away for a visit’.
1942		Berrey & Van den Bark Amer. Thes. Sl.