d.silly as a wheel: extremely silly. Australianslang.
ΘΚΠ
the mind > mental capacity > lack of understanding > foolishness, folly > [adjective] > very foolish
overfondc1592
supernodical1594
tomfool1762
damfool1881
silly as a wheel1952
1952 T. A. G. HungerfordRidge & River 57 Oscar was sound, but silly as a wheel.
1966 J. Morrison in Coast to Coast 1965–6 157 I warned Rose. She was as silly as a wheel, too, but a man's got to do what he can to protect his daughters.