Green’s Dictionary of Slang

(US) strange, foolish.

1977		L. Heinemann Close Quarters (1987) 41: We got nothing to worry about. Gooks in this neck of the woods is too dufus.
1984		A. Smith North of Montana 180: I feel giddy and a dufus grin has plastered itself across my face.
1989		(con. 1968) W.E. Merritt Where the Rivers Ran Backward 30: You dofous mothers.