Green’s Dictionary of Slang

(Aus.) foolish, stupid.

1954		(con. 1940s) T.A.G. Hungerford Sowers of the Wind 170: Then some dill padre has a go at us.
1996		J. Byrell Lairs, Urgers & Coat-Tuggers 43: At the time de Mestre had been [...] telling anyone dill enough to listen that Inheritor was by far the better of the two and should take out the event [ibid.] 143: But it wasn’t, if you were a jerry to the way his cerebral motor ticked over [...] as dill a move as it would have appeared.